For at least three days now, my downloading speed for Gmod add-ons and Steamworks Common Redistributables has all of a sudden been insanely slow, despite my internet working perfectly fine. Usually for a brief moment the downloads gain some MB but then freeze, then slowly drop down to 0. What's really odd is that this issue seemingly only applies to Gmod, as downloading from the L4D2 workshop is fine.

I've also tried changing my download regions, rebooting my connection, disabling proxy, antivirus, clearing my download cache,repairing download discs, and no luck. Is this only me, or what happened?