This might sound rediculous but I just finished researching this stupid problem for hours. What i had to do was make sure that my computer (which was one of the devices trying to connect) had "automatically set time" selected in windows. I have no idea why thats an issue but once I had the computer set to automatically detect time (in the date/time settings) it worked immediately after.
Worth a shot.
For informations sake, i was trying to connect a gaming laptop to a PS4 hosted game (using LAN and cross-platform). Neither could connect to each other no matter who was hosting the game until i set the stupid automatic date/time to on (in windows 10).
Hopefully this helps some people