look at reliability monitor report and study any error logs you have you might find the answer by googling the error codes.
have you tried your pc with ethernet connection to eliminate the possibility of a faulty or low spec dongle , my custom rig cost 3k but the wifi dongle that came with the mobo was just not good enough for gaming.
tip …. if your reliability monitor is full of loads of report you can clear them out by using ccleaner , scroll to bottom and on advanced tab tick the first item , windows event log. , the monitor will still work but it will reset if you run ccleaner again with the box still ticked.