altcloud can only work if the nextcloud FQDN is also set to altcloud.
Does it make a difference when you connect from WAN or LAN?
Does your node has the same FQDN as Nextcloud?
EDIT:
I tested it and it works.
On the NethSec are certificates and reverse proxies for following FQDNs.
All are pointing to https://192.168.0.10 which is the NS8 IP. If you have more nodes it needs to point to the right node where the app is installed.
If the node has some internal name like node.internaldomain.local it doesn’t matter but the app FQDNs need to be set correctly in the app settings on NS8. The external clients get to the NethSec anyway.
DNS must resolve the FQDNs. If you want to setup internal DNS entries for those FQDNs then they need to point to the NethSec so the clients get the valid certificate.
- Node FQDN: node.domain.tld
- Nextcloud FQDN: nextcloud.domain.tld
- Collabora FQDN: collabora.domain.tld
phpmyadmin: node.domain.tld/phpmyadmin
cluster-admin: node.domain.tld/cluster-admin
Reachable from LAN and WAN.
I noticed that you allowed 0.0.0.0/0 for the reverse proxies on the NethSec. That’s not needed as it’s the default.