Web interface issues with latest PVE

[System Administrator]

Hello,

I have installed the latest Proxmox VE 6.1-2 and when modifying  network 
information from web, the prefix (netmask) is slashed off from old 
interface config irrespective of whether I specify CIDR or not. And 
then, I cannot create cluster from web GUI with link0 address in 
dropdown if IP address has prefix (/cidr). I had to create it from CLI.

Finally, I cannot apply pending network changes from web even after 
installing *ifupdown2* (without reboot). It complains about 
subscription. Do I need enterprise subscription for that?

I am new to Proxmox. I will be grateful if anyone can help me fix those 
issue. Thank you in advance.

Regards,

Sonam