I have installed the NextCloudPi VM in Proxmox.
After changing the ip-adress to static ip there is no dns-server in the system settings in NextCloud listed:
So I have no internet connection with NextCloudPi / NextCloud.
The dns-server is listed under: /etc/network/interfaces but seems not to be taken over.
When I manually add the dns-server to /etc/resolv.conf then it works.
But after a restart is the resolv.conf overwritten and my added dns-server entry deleted.
This file is probably overwritten by proxmox. You can set a dns server in the DNS settings of your virtual machine (by default it is the host’s settings). Check the proxmox community if that is not working. NextcloudPi should just be a debian virtual machine I suppose.
Worst case: you can set up a script on boot to put a server in the resolv.conf at boot time
Not directly compatible with LXC, you can certainly make it work but that’s for sure more complicated than putting a DNS server in some configuration file.