Network Fixes: Xbox Multiplayer, Casting and Slow Downloads
Three of the repairs on the Fixes page deal with networking. They are worth knowing about because the symptoms rarely look like a network problem.
Xbox Live Multiplayer
If Xbox party chat will not connect, or matchmaking in Microsoft published games fails while everything else online works fine, this is usually the tunnelling feature those services rely on being disabled or half configured.
The fix repairs it so party chat and matchmaking can connect. Restart afterwards.
Network Discovery and Casting
If you cannot see other PCs on your home network, or casting to a TV has stopped appearing as an option, the services that announce your PC to the network are switched off.
The fix re-enables them. This is a common side effect of privacy tools and of some third party optimizers.
Slow Download Speeds
If downloads are far slower than the speed you pay for, and it is the same across browsers and games, Windows may be holding back part of your bandwidth.
The fix removes those restrictions. If your speed does not change, the bottleneck is outside your PC, and the honest answer is that no software setting will fix that.
Before you assume it is your PC
Test on another device on the same connection
Restart your router
Then run the fix
Related network tuning
If your connection is fine but your ping is high in games, that is a different job. The Network page has tweaks aimed at latency rather than repairs.
Related: Lower ping, The Fixes page.