same… packets are not going out NS7 
If a nethsec is in between you could try to delete the udp connections:
Search for 55820 for NS8 connections and for the NS7 port that always changes which is not usual and delete the connections.
From NethServer 7 migration — NS8 documentation :
The VPN address and port were configured during the cluster creation: by default the address is the leader node FQDN and the port number is 55820.
Can the NS7 reach the NS8 via the FQDN?
SOLVED
Thats was the Hetzner firewall that was blocking… Strange :
Even this doesn’t work
And I learned that debugging Wireguard tunnels is really a pain in the *** 
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Time to configure Proxmox’s firewall I guess…
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Done. THANKS @mrmarkuz
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