iPad DNS Troubleshooting

[gsk]

Hi All,

 

I have a problem where the mojority of the student iPads are often (but intermittently) having issues with connecting to the internet.

 

The iPads will be unable to connect to a website that it was working fine with a few seconds ago. If you leave it a couple of minutes it will work. If you immediately turn on Airplane Mode and then turn it off again, it will work straight away.

 

I'm using UniFi Nano HD APs, UniFi switches, Server 2012R2 as the only DC with DNS and DHCP. No VLANS in use and wireless laptops aren't missing a beat.

 

No DNS errors are coming up in event viewer on the Windows Server. The iPads are fine when I've taken a handful home to test.

 

 

Does anyone have any thoughts on how to chase this down to see what's causing it?

 

Thanks,

[round2it]

firmware on the aps might be the issue can you update them ?

[gsk]

They’re all up to date and the issues have carried over from previous updates. Thank you for replying.

[DavR]

Could the difference be between devices on the 2.4Gz band and those using 5Ghz?

 

Depending on relative age of devices, your wifi could be just fine on one band, and suffering interference on the other.

[gsk]

Could the difference be between devices on the 2.4Gz band and those using 5Ghz?

 

Depending on relative age of devices, your wifi could be just fine on one band, and suffering interference on the other.

 

Thanks, I'll check that out, I haven't looked down that route yet. I suspect not, for a couple of reasons:

1)The windows laptops are brand new HP ProBooks with AX wireless cards so should (although I've not checked yet) be using 5g most of the time

2)The issue seems to be ipad related across the site and I would expect interference to be a problem in some areas but not all

 

I'll let you know what I find re the use of bands though to see if that adds any pieces to the puzzle.

 

Thanks,

[chazzy2501]

ipads maybe using private mac address mode (as its the default now), so keep changing mac addresses when they feel like it. This might upset some systems you have in place.

[gsk]

ipads maybe using private mac address mode (as its the default now), so keep changing mac addresses when they feel like it. This might upset some systems you have in place.

I've pushed out a change to the WiFi profile on the iPads through MDM and it's still happening.

 

Thanks for the replies. It's much appreciated, as I'm really struggling with what to try next.

[gsk]

Could the difference be between devices on the 2.4Gz band and those using 5Ghz?

 

Depending on relative age of devices, your wifi could be just fine on one band, and suffering interference on the other.

 

I've checked the bands and there are a few older iPads on the 2.4GHz band but the vast majority of all devices (laptops or iPads) are on 5GHz. It definitely seems to be something the apple devices don't like - although I should probably keep an open mind so I don't go down a dead end.

 

Thanks,

[Brimstone]

How many iPads do you have, do you have a caching server, are you a LA school that shares a public I.P. with other schools?

[pete]

On the UniFi dashboard, what's the DHCP error rate looking like over a week or so?

[NicholasEsping]

Do you apply any web filtering to the iPads?

[gsk]

How many iPads do you have, do you have a caching server, are you a LA school that shares a public I.P. with other schools?

There are 80 iPads. Yes there is a caching server. It's an LA school but it uses an RM connection rather than an LA enforced RBC.

 

On the UniFi dashboard, what's the DHCP error rate looking like over a week or so?

I wasn't able to see much at all on the dashboard other than that wifi experience was at around 98%. I changed back to the classic view and it gives far more useful information. There are access points with high retry rates (Don't know what this actually means or how to fix it yet but at least it's a thread to pull on!) and there are acknowledgements that some devices aren't resolving DNS requests - but no clue as to why just yet, so any ideas appreciated!

 

Do you apply any web filtering to the iPads?

Only the cloud-based RM Safetynet that applies to the whole network.