The IMAP server just works fine without a glitch for me. What error do you get?
The CalDAV has an issue which can be solved following @3dEyes ’s brilliant tip here:
I’ve tried to add the CalDAV served by Disroot to no avail. I get this error
JavaScript error: resource:///modules/DNS.worker.mjs, line 61: Error: Couldn't find libresolv for other; tried: libresolv.9.so,libresolv.so.2,libresolv.so
console.warn: Calendar: "[CalICSProvider] Could not detect calendar using method attemptDAVLocation - resource:///modules/calendar/utils/calProviderDetectionUtils.sys.mjs:17: AuthFailedError - DetectionError@resource:///modules/calendar/utils/calProviderDetectionUtil…