What is the problem? Firefox won't connect, with the screenshotted issue. Opera gives a more generic error. Chrome gives an error too, but will allow me to bypass it. I'm guessing in the ever evolving world of internet security browsers are requiring higher encryption keys on certs, and the one in OctoPi is too low? But just a guess. Wondering, would it be possible to get OctoPi to integrate with LetsEncrypt now that that's a thing, so its cert is always valid and up to date? Don't know if it would be possible because of "domain ownership" checks by LE, but maybe somehow?
What did you already try to solve it? Can bypass the error in Chrome (for now) but not in Firefox or Opera.
Logs (syslog, dmesg, ... no logs, no support) - octoprint.log (6.0 KB)
Additional information about your network Connecting from Windows 10 to OctoPi running on Rasberry Pi 3B+