Recently I upgraded to macOS Ventura and when either Norton VPN or NordVPN is connected, App Store would not connect, Safari kept displaying "Safari Can't Open Webpage" and Apple Music kept displaying "Loading your music library" etc. But when either VPN is disconnected everything works. I tried so many things but none worked. After a few days...
Few minutes back, I went to System Settings -> Network -> VPN & Filter -> Filters & Proxies -> Disable Norton 360
Then Norton popped up notifications to fix Norton related issue. Then I enabled it again. Now everything is working as expected even when Norton or NordVPN is enabled. Looks like it's a bug in Norton 360? There's a similar thread here: https://community.norton.com/en/forums/norton-vpn-blocks-internet-new-macos-130-ventura
Hopefully it will be helpful to those users experiencing this issue. Thanks