WAP371 - clients keep stalling - high FCS errors and RTS failure count

[GuyvdWerf]

Hello,

I've tried on my own for too long to figure this out so looking for assistance please...

My home network has FTTB providing 100 Mbps down and 40 Mbps up. Clients associated to the WAP371 (FW 1.3.0.7, the latest), however, get 0.5Mbps down and ping latency is above 1s.

I've rebooted recently with factory defaults and set up 2 networks. The SSIDs are unique in the area, 1 per radio and both using a different VLAN. Security uses WPA2-AES.

The WAP LAN IP is static and on a 3rd VLAN (which is also untagged, and is the management VLAN). The trunk to the connected L2 mode switch allows the 3 VLANs.

Connection to the WAP371 UI works using WLAN or LAN.
Any connection to the SSIDs work for all clients but the connection is also extremely slow. Traffic statistics shows no dropped packets, neither transmitted nor received, but radio statistics shows relatively high "FCS Error Count", "RTS Failure Count" and "Duplicate Frame Count".

Considering that a Unifi unit (UAP AC HD) works in the same configuration and location, I would love to resolve this before swapping the WAP371 for a new Unifi unit. I don't mind the hassle, but the cost...

Many thanks.

[marce1000]

            - Make sure that the client wifi driver(s) are up to date , 

 M.

[GuyvdWerf]

Thanks for the tip @marce1000 , but I've seen this suggestion before and wondered what users are expected to do when, like me, our clients use an Android cell phone (in my case, a Samsung Galaxy S22+ with latest updates). It has never failed on other wireless APs, and drivers aren't something we can play with. As for Windows laptops, all drivers are the latest, and have also never failed on other wireless APs.

I could do a Wireshark capture, but I'm not sure what to look for. Any ideas anyone? Thanks.

[GuyvdWerf]

So another dead end. Debugging FCS isn't possible using Wireshark, even though it has the capability. After port mirroring and capturing all and any data from the unit, it became clear the FCS data isn't made available due to the OS or, most likely, the NIC driver. Makes sense - bad FCS indicates rubbish data so filtering is a good thing normally.

My last ask to the community: who has similar issues with FCS on a wireless AP? What did you do about it, other than replacing the unit?

Thanks again.

[marce1000]

- Well another thing to consider are none wifi interferers on the specific
band and or channel. So the wireless environment should be analyzed and
these small business devices don' have CleanAir. So the Ubuntu could then
only solve the problem by chance, negotiating another channel or band with
the client,

M.

[GuyvdWerf]

Thanks @marce1000
That's where I am now checking for frequency interference. 2.4GHz seems more stable that 5GHz, so there might be something.
As said before, the Unifi unit "just works" when installed and configured the same. Frustrating.

[Rich R · Accepted solution]

Sorry we can't help more, but most people here only have experience with the Cisco enterprise class APs, not the "Small Business" products and the documentation for these products is rather basic without any of the usual detailed technical documentation we expect for other Cisco products.

The product is also quite old now (AC/N) - nearly End of Life.  It passed End of Software Maintenance so Cisco hasn't tested the software or fixed bugs since 2020.
https://www.cisco.com/c/en/us/products/collateral/wireless/small-business-wireless-access-points/eos-eol-notice-c51-742550.html