PLSMC

I will be going to the other site tomorrow to do the suggested static IP test.

There is a firewall rule for routing traffic between sites. See attachment. Each site has its own DC/DNS/DHCP server. There is an equivalent Core switch at the other site, only caveat is that other site is much smaller, only 70 devices in total.

CPU loads appear fine. See attachments for examples. We are a SEND school so whilst i will not rule out a student messing with the wall ports, it is very unlikely due to their condition. In my case it would be more likely to be a teacher.

I have replaced every patch lead in our comms cabinets to ensure that there are no physical loops.

Your description of our network is exactly how it is. The DHCP scope and vlan config etc, you got it spot on. The Core switch is running Software Version 7.1.070, Release 3507 which is the previous version so i will update as soon as possible. The strange thing is that the issue does not occur during the school holidays. It only seems to occur when the network is under load. I came in today (Bank Holiday) and all reported affected devices are connected to the network. It is becoming a real head scratcher. Many thanks to everyone for your input.

Unfortunately this is the switch and what i have to work with. I cannot find anything in the GUI relating to RIP configuration ( probably has to be done through CLI) but it does appear in the statistics as per attachment. We do have a proper router/firewall from our ISP ( LGfL) I should mention that the switch logs don't contain any error messages, however it does continuously report that the "maximum number of ARP entries on the device has been reached". Is this something i should look into. It only appears as an informational log entry. Maximum number of ARP entries on the device is reached.Maximum number of ARP entries on the device is reached.maximumMaximum number of ARP entries on the device is reached.

I have attached images of the switch config relating to routing and IP helper just to confirm this is correct. I cannot see any ACL config enabled. The DC is on VLAN 1 which is the same vlan as the affected desktops but different to affected phones ( vlan 3) The output of ipconfig /all on devices on different vlans appear the same apart from the gateway entry which differs as each vlan has its own gateway IP which routes back to the core and obviously the device IP. STP is enabled MSTP. I need to look into where to find when it was last recalculated.

I haven't checked with static IP and DHCP server is on site with issue. Affected desktops are plugged into their own network port.

Only 50% in use. - - - Updated - - - Phone does power up.

I am at a split site school and at one of the sites we are encountering an issue whereby various devices, be it desktop and/or VoIP phone will not connect to the network. On the desktops, running the network troubleshooter, the error shows as unable to contact the DNS server. The desktop does have all network settings correct( IP, gateway, dns, etc) when doing the IPconfig all command. This happens to just a few devices randomly and might last a few minutes or hours or sometime days. No matter which network port i connect a device experiencing this issue it will not connect, however if i connect a working device into the port of a non working device it connects without issue. A related issue is that i do not seem to be able to connect from a device in vlan 1 to vlan 3. Once thing i have noticed is that it only seems to occur during term time. During school break all devices are able to connect and stay connected without any issue. I am also able to connect without issue to all vlans from the other site at all times. The network hardware is comprised of the following. HPE 1950 Core switch which is used to route traffic across vlans. The edge switches are TP-Link. We have 3 vlans which comprise of: computer devices, IP Phones and Paxton NET 2 doors. We have 1 physical server ( domain controller) and 1 VM for Paxton Net 2 which sits on vlan 3. I have replaced all patch leads and checked switch configs to ensure there are no loops but now i am running out of ideas. I imagine it is a switch config issue but i just cannot find it. The next step i will be taking is to disconnect all switches except the core to try and isolate where the issue might be and hopefully by adding a switch at a time the issue will present itself. Can anyone offer other suggestions on what might be the cause or where to start troubleshooting. Many thanks.