Cannot access HA anymore, Supervisor healthy and OK, CLI is fine

Installation
1

I am running HA on Raspberry PI 4 for 2 years and suddenly I cannot access it anylonger.
Here is where I am:

  • remote to HA gives HOST ERROR
  • local (via IP) gives: cannot reach site
  • ping to the PI-4 works and gives me 125ms return latency
  • advance IP scan (app) sees PI-4; WireShark tells me ‘retransmissions’ end ‘reset’ of connection to the PI-4
  • port :4357 (supervisor): all fine and healthy
  • port:7070 (evcc): works fine
  • direct screen/keyboard on PI-4 USB: fine, I get the CLI
    So, it seems that the frontend doesn’t, the backend is fine.

Now my questions:

  1. maybe the SD card is faulty. How can I diagnose via the CLI? Or, can I check it by plugging in on a Windows PC?
  2. Can I restart the frontend in anyway or can I do something to check integrity of the HA installation?
  3. How can I check the network interface from the HA CLI by e.g. ping to another PC?
  4. Any other way to get my HA back working?
2

Try

ha su repair
ha core rebuild
3

Result after core rebuild command: ERROR: No home assistant core response, assuming a fatal startup error.

What should I do next?

4

Now the SD card in the Raspberry PI 4 diesn’t work anymore.
STOP now !