Hello There,
I can help you with Upgrade Proxmox to latest 5 version. even you didn't get enterprise subscribe.
I've done it on a couple of our servers which uses old PVE (3x and 4x) and I'll handle it with the minimum outage.
Could you please tell me how many are your VM and CTs and What is your current patch exactly?
If you need further information, Please let me know
Regards,
Daniel