I guess you are on Windows 10 .. it blows!
Try this .. Right click on the main Dflw.exe file by going to "C:Program Files (x86)NovaLogicDelta Force Land WarriorDflw.exe"
Right click that file and then hit
Troubleshoot Compatibility. The screen will flicker and do whatever it has to do. You will get the correct recommendation, select the option and hit Save/Ok/Use These Settings.
Shouldn't have any issues joining the server. By the way, you don't even have to login to Nova for joining multiplayer. Search for
DFLW lobbies and you will get that file. Moreover, join the FB DFLW community, you can find good help there too.
All the best!
Enviro -AuW-