I have this BTWhole Home with 3 white disks for some years with no issues firmware v1.02.13 build07 dated 2021 nothing home wise has changed, in the last month constant probems on all disks, dropouts or unable to connect, have reset several times. Has my units reached there sell buy dates? and switch to TP-Link?
I used these discs for about 4-5 years and they are great but in some respects very limited, indeed the firmware has not been updated in years, any bugs issues since then will just remain.
I had seen a few folks lately reporting issues which seems an odd coincidence, I got rid of 9 discs few months back and there was random reboots, some discs just going red without reconnecting until rebooting the entire lot.
The default action of the discs are to auto select a WIFI channel set by the master, sometimes when the channel changes it might find itself suffering more interference, perhaps get a WIFI analyser app and find the channel with the least congestion on and manually fix the BTWholeome setup to this one.
Really though, you probably are better with DECO's.....
I have a wifi analizer app and the chanel is OK
Try logging into the master disc via its IP address on a web browser and find the setting to set the preferred method of connection to Daisy Chain, pretty stupid its not the default but there you go.