Nextcloud as external storage


I am unable to get my planned setup to work.

First some information about the setup :

I have two nextcloud servers, one on a VPS let’s call it vpsserv and another one running on a odroid hc1 at home let’s call it homeserv. Both are connected via vpn.

vpsserv is my VPN server and homeserv the client. vpsserv webserver is exposed to the internet while homeserv is not.

I tried adding homeserv as external storage (selected nextcloud as type) to the vpsserv server, but it didn’t work. Always show the red sign.

Config for adding:
Directory: /
Login via Username and Password

The other way around adding vpsserv to homeserv works (adding by domain name) but this is not what I want.

From cli of vpsserv the http server of homeserv is reachable via telnet.

I dont see any error information which could give me a hint, how to proceed.

Anyone has an idea ?