Welcome to the forum.

Sounds like either the GPS antenna is duff or the internal GPS receiver unit in the mk4.

Buy the GPS antenna first (it's the cheapest possible solution), you should get one off eBay for $10 (any female SMB push fit will do), if you have a coupe then a 3m one will be fine a vert then a 5m.

The GPS antenna attaches to the back of the mk4 and is routed to the centre (rear) of the rear parcel shelf, on the vert it's near the front screen somewhere.

But as a test, just connect to the mk4 and let it see free sky, then do the Sat test again.

HTH

__________________
Sept 03, M3, Silver Grey. Retro-fits: Modded Mk4 DVD Drive, OEM Bluetooth, VR Control, Rainbow Speaker Upgrade, Sony SOT Amp, HK Sub, CCFL, Intravee II, NightMode.