If you portfowarded, you cannot enable UPnP.
so I should disable it?
Yes
Most likely you didn't port forward correctly, did you follow a YouTube video?
Did your local IP change? Some routers have the port forward linked to your local IP. So if it's not the same, you need to update the Blockland port forward to the correct local IP.
Also, does it matter if i have Client_MissionEditor.zip in my addons folder?