To have the router accessible from outside, you cannot use hassio.local:8123, but you should use a dns service like duckdns. then in your router, forward port 8123 to 8123 on your IP for the hassio device.
(you can check portforward.com for instructions).
Does it drop when you are not doing anything? If it worked and then interrupts, that would sound like an unstable network (component).
Thanks, Piggyback. I know.
But I talk about local access (a computer on the same network as the raspberry pi)
Hassio.local:8123 works… and suddenly it doesn’t work anymore.
I don’t know why, I talk about ‘coïncidences’, things I do shortly before the connection stops working. I don’t know if that’s the reason…
Mind posting your configuration.yaml and clarify which Add-ons you have activated?
Also : Do you use SSL? have you tried from different devices / browsers?