Wifi over Windows NPS radius doesn't work when on cellular

[Andrew3]

We have couple MX68CW that has cellular sim cards as backup. And when WAN1 is offline users can't access 801.11x wifi over windows NPS. It doesn't want to connect to wifi no matter that i'll reboot check and so on.

It works when WAN1 is active though...

Any idea why ?

[alemabrahao]

Are you using the WAN or LAN IP to communicate with your NPS?

Have you collected the NPS logs to check what error occurs during authentication?

[alemabrahao]

Maybe it will help you.

https://www.cisco.com/c/en/us/support/docs/switches/meraki-ms320-48/217894-troubleshoot-recent-802-1...

[RaphaelL]

What firmware are you running on the MX ?

[Andrew3]

18.211.4 on all locations. 

[PhilipDAth]

I assume your are acessing your RADIUS server over AutoVPN?

Does AutoVPN come up over your cellular?  You might need to use a different APN.

Try doing a ping over AutoVPN over cellular and see if it is woring.

If ping does work, you might have an MTU issue, especially if you use certificate-based authentication. You can try configuring the Framed-MTU attribute on your RADIUS server for lower and lower values (1400, 1300, etc.) until it starts working (or use "ping -f" to figure it out properly).

[Andrew3]

Ping was always working. Access to autovpn is fine. Just when i want to use radius on laptop it's trying to connect and then it fails. 

i can't use different apn. i've got specific apn from ISP to have static IP 

And none of computer in that location can connecto to WPA2-Enterprise 

[PhilipDAth]

What does the RADIUS server say?  If you are using NPS, filter the security event log on event IDs 6272 and 6273.

[Andrew3]

Change in MTU Helped! It works now.  i've set it to 1344