upgrading

The nodes of my Proxmox cluster are on version 7.1 of Proxmox. I would like to just upgrade one of the nodes to 8.0 and let it run for a bit to see if any unforeseen problems come up before upgrading the rest of the nodes. Would I be able to do this?

Hi, I'm so sorry if my problem is just a little one but since i've followed the guide to upgrade pve5to6 ( https://pve.proxmox.com/wiki/Upgrade_from_5.x_to_6.0#Upgrade_the_system_to_Debian_Buster_and_Proxmox_VE_6.0 ) i can use proxmox anymore, no webgui, and it seems that my VMs are not UP I...