The hydraguard runbook.md disagrees with itself about the hub IP:
Hub server | 141.227.136.199 (OVHcloud b3-16, Brussels EU-WEST-LZ-BRU-A)SSH | ubuntu@141.227.136.12DNS resolves hydraguard.experiencenet.com to 141.227.136.199 — that is the correct value. Line 24 should be ubuntu@141.227.136.199 or, preferably, ubuntu@hydraguard.experiencenet.com (same redaction posture we applied to the public hydraneck docs today).
Replace line 24 with the DNS hostname. While in there, audit the rest of the file for any other stale literal IPs and prefer DNS names.