[FIXED in latest release!] No connectivity for a few seconds after connecting to WiFi

[david_fuchs]

I have 3 Ruckus APs (720, 710, 510) connected to a switch, which is connected to a router/DHCP server/DNS server.

When connecting a client device to the WiFi network, there is a short period of time (1 to 2 seconds) immediately after the WiFi connects where the client is unable to reach the network. 

The issue only happens immediately after connecting - after those 1-2 seconds, the WiFi on all my devices works great, is rock solid, and blazing fast. And - it only happens on 5G, or at least, this delay is much longer on 5G than 2G. It happens on all 3 APs.

Why does a delay of a few measly seconds matter? It matters because Android uses network unreachability detection (NUD) to determine whether it's connected to a usable network. It does so by sending ARP requests to the default gateway. If NUD discovers the network is unreachable (i.e. no responses to these ARP requests arrive), it terminates the WiFi connection. Sometimes, NUD triggers before this weird problem fixes itself.

As a result, my Android phone sometimes takes 2, 3, or 4 attempts until it successfully connects to my WiFi. This is particularly annoying during roaming, as the wifi drops when walking around the house.

Is someone else observing this behavior? (The issue might also be on the client side, or with the switch, or with the router - but the fact that it is limited to 5G makes me very, very suspicious of the AP: EDIT: Yep, the culprit is the AP/Unleashed. I'm really peeved to find bugs like that in a networking device with a $1200 MSRP.)

Thanks,

- Dave.

[syamantakomer]

@david_fuchs If you look at the Access Point column, DHCP Ack is crossing it and clearly indicates that traffic is passed to the Client. Now in this case, packet captures on 3 nodes needs to be done.

1. AP eth and wifi interface (OTA capture).

2. DHCP server.

3. On client

If we run capture on all the devices, we will know where is is failing

[david_fuchs]

There ya go:

Packet capture shows DHCP requests highlighted (probably hard to see, but the timestamps match exactly). Ruckus debug tool claims both those requests received responses; both responses never show up in the capture. 

So, yeah... a $1200 "enterprise grade" networking device is dropping frames. Great.

[syamantakomer]

@david_fuchs please open up a support case if you have support contract so that support can look into the issue.

[david_fuchs]

Thanks again Syamantak!

I do not have a support contract with Ruckus.

Since this is pretty clearly a bug in Unleashed that causes unnecessary packet loss and disconnects, it's something Ruckus should fix, support contract or not. I'd be happy to share capture files or any other relevant information if contacted by someone on Ruckus' engineering team.

Best,

- Dave.

[david_fuchs · Accepted solution]

I spotted this little gem in the "resolved issues" section of the release notes for 200.12.10.5.234:

Issue ER-10340 The UE loses network connectivity when roaming between radios in the same AP, in WPA2 WLAN

So I hit "upgrade" and held my breath...

And, sure enough, it looks like the issue is fixed, or at least the behavior has massively improved compared to before!

Someone at Ruckus listened - THANK YOU!!!