I've just tried to update the firmware this evening.
It didn't seem to apply to all the discs and the end result appeared to be they factory reset themselves. The discs all reverted to broadcasting the original SSID.
I factory reset each disc individually via the button on the back of each disc and set them back up with wifi backhaul.
I switched back to ethernet backhaul and the app told me it was a new network again so I had to complete the initial set up routine (selecting pack size, naming discs etc).
This happened twice.
On disc names, the home screen of the app was showing "new disc, tap to configure". The next screen showed no name, but the disc details screen did show the name I had previously given the disc.
It was only after things had stabilised that I configured the custom SSID.
Devices have now connected back up. I've tried to restore device settings from a backup but it was unable to restore anything (crosses for each item in the list).
Does the device backup include data usage information? I've not noticed device setting restores recovering that information before. Nevertheless I seem to have full data usage information so not sure if that is because I tried to restore device settings, or the factory reset hasn't worked...
Will wait and see whether this version is any more stable than the previous which was a complete car crash.
Bad news
Looking in the premium disc gui this morning it shows both Ethernet backhaul disc's rebooted around 7:08 (15hrs ago) at the same time, so they never made it to two days uptime, however this has rebooting both Ethernet BH disc's not just the downlink discs as it did on previous fw's ! i will continue to monitor give it a fair test.
Not upgraded firmware yet but this is the kost stable I've had these. The only thing I've fone is not change ssid. Can't see why it should matter but wondered if others have always changed theirs
As far as I am aware the new WiFi 6 disc (grey disc's) uses this firmware, premium = SGA B 20832C, grey wifi 6 = SGA C 20832C as per title! There was a chap in previous thread has both premium and wifi 6 grey discs and confirmed they both use this firmware so hardware must be simliar and both have same issues so don't think about running out and buying the wifi 6 as you'll be just as disappointed.
Happy for bt to exchange them for grey ones
Looks like there's still problems with this firmware - I sayed on 822C as that was the most stable but still only lasted 5-6 days before starting to reboot the router connected disc.
@foz does you clearing of the data still temporarily fix the issue.
I managed to get hold of 3 of the BT Whole discs to test (not premium). They have been faultless - up solidly for two weeks - had a power cut in the middle but discs simply came back online.
eero 6 has been faultless too.