We have the following setup at the office:
- Windows Server 2012 DHCP
- Unifi AP (one of these rounded beauties) set up to use WPA2 with AES
- Zyxel ZyWALL 110 as firewall
Some of the clients (laptops) have static mapping, some of them (mostly the cellphones) are using IPs from the dynamic pool.
What happens is that random devices about once in 1-2 weeks loose network connection - i.e they cannot connect to any other device, nor the internet.
Common things across devices:
- the IP address looks fine
- DHCP renew does not help - they fail to contact the DHCP server, while other clients have no problem doing so at the same time
- DHCP server logs say that the device managed to renew its address properly
- the AP status page says that the client is associated
- no such problem has been known to happen to wired clients
For the laptops that are running Windows 8.1/10:
- it is enough that we switch the wifi adapter off and on (from Windows, not the kill switch on the keyboard) - they get back connectivity right after reconnecting to the network
For the Android devices (5.0+ too), it seems more persistent:
- tried restarting the phones & the APs, nothing works - they just sit on the wifi, without being able to use it (small exclamation mark next to the wifi icon).
- looking at the routing table, the office gateway is there, but it is set not to be used
- tried pinging the cellphone from another office machine - and it responds
- tried pinging anything in the office from the phone - does not work
- traceroute tries to go via the cellphone network (because of the wrong routing table I guess)
- going home, the cellphone works perfectly with my own wifi - back at the office, same problem
- it goes away after some time - few days/weeks/months... and then it appears again
Happens to iPhones too, but have not tried debugging there.
According to colleagues, they had problems with the wifi when they used another kind of access point. Not sure if it was the same problem.
I am going a bit crazy because of this - any ideas? Where should I look, which device, what tool, what log...?