Thats frustrating
I second the notion that your ip was banned by nc's brute force detection
The silent reconnects of a DAVx client on a phone could easily trigger this
You can whitelist your home routers ip in the config IIRC Maybe not on the LISO container though, IIRC it is less configurable, but doesn't "just work", I'd ditch that not nextcloud
Quick fix could be to "DELETE FROM" (or "TRUNCATE" if you are certain nobody is blocked correctly) the table bruteforce_attempts (or smth similar). Although that "dc up && dc down" worked could indicate another issue, as you do seem to have persistence with your db in a docker volume (cred are still there) which would mean the time penalty ran out during restart or oits somethimg else
Good explanation.
This has the interesting implication that the relative speed between the portals is "added" to whatever goes through it.
Example: the blue portal is on a train running with the same speed in opposite direction. The people-bundle would instantaneously be accelerated to twice the speed of each of the trains. (This becomes a real headscratcher if you were able to put the portals in a particle accelerator)