Lets Encrypt didn;t work after updating 2 of my 3 AX86U routers at different locations (the third used its own Global CA Authority Cert). I had to toggle AUTO and back to Let's Encrypt under DDNS settings to work around and make it get a Lets Encrypt cert.
Also, this may have been broken in past release, but the "SITE SURVEY" part of "WIFI RADAR" doesn't seem to work on any of my 3 AX86U routers. The SCAN button does nothing. The rest like 'Channel Statistics' and 'Advanced Troubleshooting' seem to work OK.