Thanks so much Rune! My issue was similar. NetworkManager didn't have the wireless password for the network I was trying to edit.
You should be able to click save always, but there should be some sort of popup like:
"Warning: Network Manager can't confirm with your router this IP address is valid. Please check the IP address you entered and/or your wireless password. Or click continue to continue with these settings."
Thanks so much Rune! My issue was similar. NetworkManager didn't have the wireless password for the network I was trying to edit.
You should be able to click save always, but there should be some sort of popup like:
"Warning: Network Manager can't confirm with your router this IP address is valid. Please check the IP address you entered and/or your wireless password. Or click continue to continue with these settings."