I recently upgraded my AP802 to V1.3.5 (from V1.3.4.1); it claims to fix a few Wifi security issues, that I wasn't aware of.

//Removed incorrect problem decription

UPDATE

When this problem was first noticed, it coincided with the AP802 having been recently been moved to a new location, where it was sharing a network connection with 'dumb' devices. This meant that the Netgear switch to which it was ultimately connected, had quite an 'odd' configuration. This was causing its own issues - though those issues are definitely different with V1.3.4.1 and V1.3.5 firmware loaded.

See my next post, for a more organised test, with the AP802's uplink device 'properly' configured.

Funnily enough I saw something like this on my router (2926ac) a couple of days ago. I was playing around (again!) with my mesh settings and noticed on the router dashboard that one of my IOT devices, which should have have a 192.168.3.x address on SSID2, appeared to have been given a 192.168.1.x address, even though it was still (apparently) on SSID2.
I think I had to delete the offending device and re-add it, all appears to be well now.

I moved my AP802 to a location where it could be plugged into its own port on a Netgear GS105E, with the VLAN tags set correctly. I renamed the 4 SSIDs (2 per band), to be unique, so I could be sure which one I was connecting to.

With V1.3.4.1 firmware, I can connect to each SSID in turn and see DHCP complete almost instantly and return an appropriate IP address. Using the speed tester at https://fast.com , I can see that the connection works (and at the expected speed).

With V1.3.5 firmware, I get the same results but only on the 2.4GHz band.

Selecting the two SSIDs on 5GHz, results in a very slow DHCP negotiation (though it does eventually complete and return the correct IP address). My phone then says "No internet connection, do you still want to connect?". If I say "yes", it appears to be connected, but simply does not work. The speed tester site either hangs, or starts using Sky Mobile

I've downgraded and upgraded a few times, to satisfy myself this is a reproducible bug.

I thought I'd better try a few more devices. (Huawei P9 phone and Samsung SM-T800 tablet)

Same results (or worse, if that's possible). They were reticent to connect to 5GHz at all.

Did Draytek forget to test this release :?:

Don't know the answer to that, but this is eerily reminiscent of the problems I had with 5GHz on AP902s. Touch wood the AP903s don't seem to have this problem.

The symptoms are almost what you would get with a very weak signal ... failing to connect - or eventually succeeding, but then not actually working.

I didn't take a note of the signal levels, so I suppose I'll need to repeat the exercise