Cannot to Can’t connect to homeassistant:8123 but can connect to homeassiatant:4357

hi guys.Today, when I used homeassistant, I found that port 8123 could not be accessed, and the connection was denied, but port 4357 showed that everything was normal. Can anyone give mea clue? Thank you very much

I do have the same issue for some days yet.
After rebooting it works for some hours. At at one point no connection to port 8123.

Portscan says that port 8123 is open. System is pingable.
I tried several thing. New SD-Card with a fresh installation and restore from backup - same thing