Since Windows 10 we are challenging huge difficulties in Internet connection quality. Whenever there pops up a computer in the network which is just updating itself via Windows update (with P2P setting (Delivery Optimization) enabled (even "LAN only"))  the whole network in the location "goes down". That means horrible connection quality, even just surfing the web is a problem.
I am speaking about places/houses with 10Mbit symetric connections. Immediately after disconnecting the PC from the network, it works normally. Windows P2P updates is the only source of trouble in the network. Even massive FTP Up/Down usage and/or HD Youtubeing does not cause issues - the connection is just slow, but usable.
I've already disabled the Delivery Optimization via GPO, but the problem is with private computers :(
We have no application-layer firewall available, have to stick with "simple" FW capabilities (ports). We have physical FW installed.
Is there any possibility how to block it effectively using ports?
Does it use some non-changing ports?
What about updating via standard Microsoft servers - would it be affected?