wireless issues all of a sudden

[mernoobnetwork]

we have had meraki mr44 and 76s for a while now, and one site starting having issues with radius timeout issues

then the issue would pass and come back

now im getting a few more sites are starting to report issues.

we have toggled client balancing, fast roaming is off. anything else we can look into

 we are using windows servers for radius (NPS)

[DarrenOC]

Are the issues happening in certain spots or is this a site wide problem? 

I had one client who literally couldn’t use their devices in a certain area. After running some survey software I found 2 old APs on the network that were broadcasting the same SSID.  Once removed…all was well.

[BlakeRichardson]

1. How many client devices are you supporting?  
2. Is the NPS server being over utilised? 
3. Is the problem site wide or location based?

[mernoobnetwork]

location specific

its not a coverage issue

all other sites are ok, and im talking about hundreds

[BlakeRichardson]

Just confirming by location specific do you mean a single site out of multiple sites or a location within single site? 

[mernoobnetwork]

multiple phyiscal sites

but over a 100 work no problem

[cmr]

@mernoobnetwork for the site where you have the problems, is it all over the site or for particular APs?

[mernoobnetwork]

the entire site

[mernoobnetwork]

our guest network is ok, but doesnt use radius

[BlakeRichardson]

And each site is connecting to a single NPS hosted via a site to site VPN or does each site have their own NPS? 

[mernoobnetwork]

single windows server nps in a dc

yes tunneled back

[PhilipDAth]

Painfull!

Maybe it is a bandwidth squeeze.

Try configuring the WAN uplink bandwidth (on your MX) to match what it actually is.

Then then create a QoS rule to make the RADIUS traffic high priority.

More general information:

https://documentation.meraki.com/MX/Firewall_and_Traffic_Shaping/SD-WAN_and_Traffic_Shaping

[mernoobnetwork]

the issue has started to spread to multiple sites

it will stop working, then start working 2 hours later

looking at our nps servers, as that is the most central issue

nps event mainly around malformed packet/request

[Networking101]

What firmware you are running and what logs or error do you see on Meraki dashboard, End machine and NPS?

[pjc]

Are you using EAP-TLS certs etc for authentication to NPS ?  We have seen similar issues at a few of our sites caused by some sites having lower MTU values resulting in packet fragmentation when using certs and VPN connections.  We tried lowering MTU packet size on NPS connection policies without any success.

Ended up using Meraki Radius Proxy for those sites with the issue - as it's sent directly out over the internet for this, then you don't get the VPN encryption overhead and the auth packets are not fragmented

Good luck