For support DA needed i think
Browser used and version
DA versions used also OS and custombuild versions
When the cert is or should been udpated by letsencrypt.
Do you still see for that domain(s) at ssl the lestancrypt cert?
Or is it only for the DA panel at port 2222 ?
Other domains ok?
I can't help but these info's could be important!
Also look in docs where to find versions or the letsencrypt renwed yes or no in ssh for the hostname.
Do you use hostname as "vps.exampledomain.com " ?
What is example.com as domain doing ?
IPV4 or IPV6 at your place connection where you use the browser to login?
Server itself yes or no in ipv4 ipv6 or both?
Do you use forced ssl, and or also redirect www or non www settings in DA panel or somewhere else.?
You can have that force also set for DA ADMIN PANEL a check checkbox somewhere i don't know by head , is that set or not set?
Test with online testers the ipv6 on https and http!
and your browser own connection to.
try other browser other computer other internet connection.
Test check your dns and nameserver also online for ipv6 and ipv4!!!!
FYI i have problems some times to as testing on
https://en.internet.nl/ then sometimes seems random on ipv6 no https , wen testing same time however with a ipv6 online tester on https no problem.
No errors in log on server however at that DA BOX centos 8 alma latest DA and custombuild.
OYEA sometimes if new cert or config a browser need a kind of reset cookies and co , mostly this is only with ftp programs but sometimes check browser on caching things.
If it is browser that is going wel after there reset and clear al cookie, sessions, cache, then nogood and mayby kind of BUG DA