'Keep me logged in' not working when accessing via hostname

Hello! There’s one little issue that I’d like to solve, but I don’t know where to start.

I got HA Supervised working on top of Debian 11. I also ticked ‘web server’ and ‘SSH server’ during the installation of Debian. Its IP address is set to static from my router settings.

I can login to HA either on or on debian.local:8123.
If I access the dashboard by the hostname, it will log me out after each visit / refresh.
‘Keep me logged in’ has no effect. This does not happen when using the IP address. It never logged me out from

The same thing happened when I tried to ssh (preinstalled by Debian): remembering me on the address, forgetting me on the hostname (It asked me to type ‘yes’ every time before the password). But this solved itself with a reboot.

Is this an intended security feature? Or an issue with Debian, my browser, HA or my router? I have a mesh network with TP-Link Deco units. The network settings are very limited.

Thanks for reading!

Looks like deleting my browser cache and cookies fixed it! At least for now?