Hello.
Here is the plan to move the server.
1 : redirect via proxy pass on the actual server to new server, server Monday 1 at 9 h am french hour. (please no job on jenkins)
  1a : check all is OK
2 : migrate dns , the new IP is 212.47.240.49 galen can you do it? maybe Tuesday 2.
3 by by old server.
4 i'ts possible to create a TLS certificat for https transaction ? CN jenkins.koha-community.org  ?? -> galen again ???
Thanks Chris for the jekins admin access.