Can't connect to any matches in Halo 5

Okay so here’s the run down to prevent stupid answers like did you turn it off and on again… I had been playing halo 5 constantly about 6 months ago until I came across this error. Whenever I would search for a match it would find one do the whole connecting to players spiel and once the loading bar got to its final “segment/section” it would then throw up the error “problem with dedicated server”… I have been trying off and on for the past 6 months. I’ve uninstalled the game and reinstalled and moved it to different external hard drives and my internal. I’ve tried wireless and wired Internet… I feel like I’ve done everything imaginable. This is the only game I have problems with the rest are fine… Anyone have an idea what this might be?