I just migrated from PI 3 w/sd card to a Pi 4 with w/ssd and am having an odd issue with connecting via my DuckDNS address. Before the migration everything worked perfect.
When I connect to https://mydomain.duckdns.org internally or externally I lose the connection about every couple of minutes for 20 seconds then it is fine again.
When I lose the connection, I can still get to https://myipaddress:8123 no problem, internally of course.
The only change was modifying my router to open port 8123 → 443 to the new mac address/IP of the Pi 4’s wireless connection.
Any thoughts on what to look at or how to diagnose?