MrBrownPr

Is there any option that doesn't involve spending money? A quick look on eBay (if you know of other/better suppliers for refurbs please let me know!) suggest I am still looking at around £600+. (It's also huge and won't fit in my current cabinet without a lot of work...)

I did suspect that, but my Google Fu couldn't provide a definitive answer as to whether it was a layer 2 or layer 3 switch. I even found references to it being a "layer 2+", i.e. a layer 2 with some features of layer 3 which further muddies the waters!

I'll put my hands up straight away and admit to being something of a novice at networking and this has me stumped. We recently discovered that when our Aerohive WiFi system was installed the company that provided it included in the cost a 5 year management licence. That expired and we suddenly found ourselves unable to change settings on the APs. When we enquired with Aerohive they wanted us to pay £2,800 per annum, money we definitely did not have. Our only option was to switch over to Aerohive Connect but this meant losing the DHCP facility that we were using on the APs for some of our VLANs. I setup new DHCP ranges on our server over Easter and all seemed fine, but once we had everyone back in the school it was clear the network was being absolutely hammered, laptops would be allocated IP addresses by the DHCP but would never receive them, people wouldn't be able to access the internet or network resources, etc. Connecting to the core switch I could see constant "ARP table is full" messages. I adjusted the configuration and had one of the VLANs pick up addresses from the DHCP on our Protex box, sacrificing the guest WiFi network in the process. ARP table was no longer showing as full and people were able to access the network without issue again. The core switch is a 3COM 4200G. It seems the ARP table limit is 256 entries. Aging timer is set to 20 minutes. I'm looking for suggestions about what I can do here. Preferably suggestions with zero or at least very little cost. I'm thinking that I somehow need to get a separate DHCP to provide addresses to clients on one of our VLANs so they are not passing through the core switch and being added to the ARP table. I've considered whether we need to replace the core switch but I am struggling to find details of switches that have a higher ARP table limit. I don't want to spend money to find myself in the same boat. And I also have a nagging question at the back of my mind about whether the ARP table is really the problem or just a symptom of a different issue that needs fixing? Open to any and all suggestions, please!

What about Raspberry Pi Desktop? I've used it to revive a few older laptops: https://www.raspberrypi.org/downloads/raspberry-pi-desktop/

I have the offline installer for Windows Essentials 2012 in my Dropbox here if you want to grab it: https://www.dropbox.com/s/df33h0keizaphxo/wlsetup-all.exe?dl=0 I use DVD Styler to create our DVDs for Christmas shows, etc. Free and easy to use: https://www.dvdstyler.org/en/

Ha! That was my first thought! No, they are clean. No bent pins either! (Awful design, but that's another thing...)

Thanks, but I don't think so. We're still on Windows 7 here as the drivers supplied by Dell/Intel for the graphics cards in the majority of our laptops in Windows 10 didn't support multiple displays. I should probably also mention that it wasn't just a lack of display, none of the USB devices connected to the laptops via the dock were working either.

We use Dell laptops at my school and have docks in all the classrooms to the teachers can "quickly and easily" dock/undock their laptops for connection to the Smartboards, visualisers, etc. These docks are the absolute bane of my life and cause SO many problems! On Friday one of the teachers told me at lunch that her Smartboard had stopped working and asked if I could take a look at the end of the day. She didn't need it for the afternoon but would for this week. The docks usually have a blue power light illuminated but this wasn't showing. I checked the PSU and plug, everything was fine. I double-checked the power of the PSU and confirmed it was 130w. I swapped the dock for one in a spare classroom, still nothing. Finally I connected all the cables directly to the laptop and that worked perfectly. So it seems that there is an issue with this laptop and the connection to the dock. However, I had already had a similar issue with another laptop (slightly different Dell model) in another classroom the previous week. I'd resorted to the same resolution there, i.e. all cables direct to the laptop and removing the dock. This morning (Monday) I've come in to find a third laptop in yet another classroom with the same symptoms. This can't be a coincidence, can it? I'm thinking either a Windows update or a driver update has borked the connection between these laptops and docks. Has anyone had (or having) a similar problem and can shed any light on a solution? Thanks!

We are looking at getting some Android tablets for children to use in class. We already have some iPads and these work great with the Protex proxy server, but having tested a couple of Android tablets it seems that they don't play as nicely. While web browsing is generally fine, many applications will flat out ignore the proxy server settings and therefore can't connect to the internet when needed. I seem to recall stumbling across a post on here recently where someone had managed to configure a transparent proxy for Protex but I can't find the thread now. Does anyone else have any experience or advice on this? Thanks.

Ugh. Still struggling with this! The AeroHive APs we are using are set to support 100 clients each. We have them in almost every classroom, so we are getting nowhere near their capacity. As above, we should have plenty of capacity on the APs, so I can't see this being the issue. The AeroHive APs are PoE. I really don't think the issue is with the laptops communicating with the APs, as I can login to the AP management interface and see that the laptops are connected. And as I've said before, the laptops have all the correct information, i.e. IP address, DNS and DHCP addresses... just can't access the network shares or the internet! I would LOVE to hear more about this! We had an engineer in on Tuesday from our tech support company. He was hear two hours, said he didn't know what the problem was either and left. Not heard from him since! Yes, tried setting the APs to half-duplex, didn't make any difference unfortunately. Oh, and while I remember, I have done an arp -a on a laptop with the problem and one without and the outputs were identical. Here is the text from the email I sent to the engineer last week, giving a summary of the problems I'm having: Does anyone have any suggestions?

Update on this as I am really starting to tear my hear out with it! Firstly, the problem is still on-going. I've looked at everything I can think of. In a nutshell, the problem is that if I turn on 15 laptops at a time in one room, only around 10 of them will get a network connection straight away and will work fine. The others will show an IP address if I do an ipconfig, but will have NO internet connection. Pinging anything on the network (I usually use the proxy server's address to test) just times out. After waiting anywhere from 5 to 20 minutes, the affected laptops will eventually gain full access to the network. This is without me doing anything more than running a ping using ping xxx.xxx.xxx.xxx -t so I can see that the timeouts have stopped and we've started to receive responses. I don't have laptops that will start with a connection and then see it drop and later come back. If a laptop gets connected when I turn it on, it will stay connected. Server is running Windows Server 2012 R2. Clients are all Windows 7 laptops currently, although I have seen the same problem on Windows XP and Ubuntu. These are wireless connections through Aerohive APs, all of which have been updated to the latest firmware. DC, DNS and DHCP are all on the same server. We also have a secondary DNS and disabling this has made no difference. Any suggestions? Any other info required?

Unfortunately, all the APs are on the latest firmware and it seems to happen everywhere! I was starting to wonder if it is a problem with one of the switches, but I've no idea how I am going to start to diagnose that!

This morning I disabled one of the DNS to see if I could rule out an issue between them. Had the laptops out this afternoon and it was no better. Couldn't do an arp -a as these were the Linux laptops and I wasn't sure of the equivalent command. Any new ideas?

Just found this one in my bookmarks: Code Kingdoms

Code Combat looks excellent, I will be suggesting we use that in some lessons next year! Out of curiosity I tried the website on my iPad. I wasn't expecting it to work, which it didn't, but I did get a message to say their native iOS app is awaiting approval from Apple. Will definitely be interested in that when it is available!

Thinking about this, wouldn't this affect all clients if there were network loops? I'm confused! Was considering doing this actually, so will try this today and see if it makes any difference. Nothing ventured, etc.!

Anyone using GDevelop with their students? I run an after-school coding club once a week and originally started the students off using a local version of MightyEditor (MightyFingers | HTML5 Game Editor | Web Based | MightyFingers) which was going fine until we got to the actual coding part. The amount of complaining I got from them when I asked them to type in 2 lines of Javascript code was almost deafening and it took me most of the session to go round all the computers fixing all their mistakes! I then tried setting up files containing all the other snippets of code we needed for our game for them to copy and paste in, but even that was fraught with problems with students pasting things in the wrong order, or missing some lines when copying, etc. Aaaaaaargh! I decided we needed something a bit simpler and looked around at alternatives. I liked Construct 2 (https://www.scirra.com/construct2) having used it before so was planning to put in a budget bid for a site license, but then I realised we wouldn't be able to use it on the Linux laptops we have. That was when I found GDevelop (GDevelop - Create games without programming - Open source HTML5 and native game creator). It's free and open source and runs on Windows and Linux with a Mac version in the works. Even better, they also have GDevApp (https://gdevapp.com/) which is a browser-based version which you can use on iPads, tablets, Chromebooks, etc. So far the students are finding GDevelop much easier. It has a visual-coding element similar to Construct 2 (and to a lesser extent, Scratch) which I'm finding a little bit less restrictive than Construct 2. I'm hoping that next year we will be using this in coding lessons, I've already started installing it on all the student laptops! Definitely worth a look.

Thanks, I've run "arp -a" from a working laptop and saved the output to compare next time I have an issue. Will update here later!

Thanks for all the responses so far, here are some answers to the various questions raised: WPA2, but had the same problem using a RADIUS authentication server. I switched the student laptops to the secondary (WPA2) WiFi network in the hope that it would alleviate the problem. AreoHive APs, all their firmware is up to date. Latest WiFi drivers available from Dell for the Windows 7 laptops and I believe the Ubuntu laptops have the latest Broadcom firmware/drivers - I always find it a bit tricky to tell with Linux! Not as far as I am aware, but like I stated this isn't a Windows-exclusive problem, so I don't believe it is a problem on the laptops themselves. Still, I am willing to try anything at this point so if you can point me to where I can read up on this I would appreciate it. Not sure I follow what you're suggesting I do here. I have tried pinging various things, the domain server through both it's hostname and IP address, the proxy server by IP address, the DNS by IP address and other devices connected to the network by both IP address and name. What else do you suggest? Only one domain controller on the network. We have two DNS though, but like I said earlier when I check ipconfig on the affected laptops the DNS address is listed correctly. As above, AeroHive APs. And again as above, I've tried testing using both IPs and hostnames. What's next?

I have set up some Ubuntu laptops here at my school and getting them to work properly with the Proxy server was a huge pain! Here are my notes I made at the time, they might help you out: [b]Proxy[/b] Proxy settings in Linux are complex and frustrating to say the least! System-wide proxies in CLI Ubuntu/Server must be set as environment variables. Open the /etc/environment file with vi (or your favorite editor). This file stores the system-wide variables initialized upon boot. Add the following lines, modifying appropriately. You must duplicate in both upper-case and lower-case because (unfortunately) some programs only look for one or the other: http_proxy="http://myproxy.server.com:8080/" https_proxy="http://myproxy.server.com:8080/" ftp_proxy="http://myproxy.server.com:8080/" no_proxy="localhost,127.0.0.1,localaddress,.localdomain.com" HTTP_PROXY="http://myproxy.server.com:8080/" HTTPS_PROXY="http://myproxy.server.com:8080/" FTP_PROXY="http://myproxy.server.com:8080/" NO_PROXY="localhost,127.0.0.1,localaddress,.localdomain.com" apt-get, aptitude, etc. will not obey the environment variables when used normally with sudo. So separately configure them; create a file called 95proxies in /etc/apt/apt.conf.d/, and include the following: Acquire::http::proxy "http://myproxy.server.com:8080/"; Acquire::ftp::proxy "ftp://myproxy.server.com:8080/"; Acquire::https::proxy "https://myproxy.server.com:8080/"; Next we need to edit the /etc/nsswitch.conf file. Alter the line that begins with “hosts:” so that the entry “dns” appears on the line BEFORE the “[NOTFOUND=return]” entry. Finally, logout and reboot to make sure the changes take effect.

The file mentioned, config.txt, can be edited on another computer. The SD card will have a (small) FAT32 partition that contains config.txt and some other files to boot the Pi. If you take out the SD card and stick it in another computer you should be able to edit config.txt and set hdmi_safe=1. If that works then you can play around with other settings in config.txt. I think what you might actually need is hdmi_force_hotplug=1. You can read more about config.txt here: RPiconfig - eLinux.org

Not sure if this is the right place to start looking for a solution to this, but I've tried everything else I can think of so I am sure this must be server related! In our school we have trolleys of student laptops that we use in lessons. We usually use around 15-16 laptops in a lesson so we have 1 laptop between 2 students. When we turn them all on together they all connect to the Wifi and receive an IP address, but some of them will have no network access for a period. This period can range from a few seconds to 10 minutes or more. Some note: - This does not affect the same laptops every time - It is not always an exact number, some days you turn on 12 laptops and they will all be fine, another day you can turn on 12 and only 9 will be properly connected - This isn't just a Windows issue, we have Ubuntu laptops that are similarly affected - Checking ipconfig shows a valid IP address and correct addresses for the DNS When a laptop has no network access I mean that nothing is working, no ping, no nslookup, no access to network shares, no internet access, nothing. I usually start pinging our proxy server and leave the laptop until I can see that the pings are getting responses and then I know that all network connectivity is restored. Any suggestions?