If your connected through a router then enable UPnP and give access to L/W
In settings.
If you need help with that, post Router make n model.
Who is your ISP, Some filter or Cramp P2P traffic.

Ps..Sometimes If you Cancel L/W permision in Windows Firewall with L/W closed, Then restart L/W and reaply full
permision it fixes itself.
Peace.

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mickjapa108