From OVH to OVH, same network. Same data, same OS and with same plesk.
I will update the domain forwarding and DNS myself.
All databases etc need to be moved. There is 1 SSL certificate.
The server hosts a few domains and smaller sites, hence we are downgrading.
Generally i think you could do a plesk back and restore here and move the data across using FTP. Speeds will be over 30MB as same network so it might not take long.