hi,
I am trying to install HA on a smaller memory, but now the new and the old versions both refused to connect on port 8123. Same problem occurs on two different laptops and the android app. I am using a RP5 with wired ethernet. Ping works, observer on 4357 works. I have shut down and restarted all devices. What has changed? What to do?
Same problem here run the update. Install is on a NUC PC and no web interface. Ping is possible and observer 4357 signs no problems. Please help??
What does the monitor output on the HA server tell you?
sytem is running, IP addresses, etc.
You have both WiFi and Ethernet connected.
Both connection will then try to claim the homeassistant.local address.
No idea if they will eventually resolve it, but my best guess is they will keep fighting each other.
then connecting to 1 of the ip adresses (instead of hostname) would work.
This is the old HA, the new one only has ethernet, but the same issues. There is an other problem.
the old version started working again 
You have two HA installations running?
Did you change IP on one of them, so they do not use the same?
And if you want both running then you should also change the server name in network settings on one of them.
I have the old one running. The new one has a different IP address. I will try the new one again later, but not today.
Are you installing 2025.12.x? if so add the version to the title.
It helps people observe trends in the data.
This might also help. How to Troubleshoot Raspberry Pi Crashing