I try to match up and it takes a while to matchmaking and it shows an Error:Ghost Rexon Wildlands services are not available at this time
Please try again later
Tarija-00100
I had a lot of trouble with another game from Ubi-soft. The right thing to do, what worked out great for me, was to call "customer service" in my country.
They were very friendly and helpful. It took a while, but my problem got eventually fixed.
Having helped a neighbour just within the last 12 hours (albeit on xbox version), if your NAT is on anything other than "open" try using a different port. This fixed my neighbours issue immediately earlier on after he had spent over an hour with matchmaking issues.