1. PC
   • Steam Client: https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711
   • Uplay Client: See “TCP” under “Games\Tom Clancy’s Rainbow Six: Siege\PC”
   • Battle.net: https://us.battle.net/support/en/article/7842
   • Epic Games Client: See “Games\Fortnite\PC
      
2. STEAM: 

   Required Ports for Steam

   The following are ports you need to have open on your router or firewall for Steam to operate normally.

   To log into Steam and download content:
    

HTTP (TCP remote port 80) and HTTPS (443)

UDP remote port 27015-27050

TCP remote port 27015-27050

Steam Client

UDP remote port 27000-27100: Game traffic

UDP local port 27031-27036: Remote Play

TCP local port 27036: Remote Play

UDP remote port 4380

Dedicated or Listen Servers

TCP local port 27015 (default): SRCDS Rcon port

UDP local port 27015 (default): gameplay traffic

Steamworks P2P Networking and Steam Voice Chat

UDP remote port 3478

UDP remote port 4379

UDP remote port 4380

UDP remote ports: 27014-27030

Note: Many schools, universities, business networks and proxies block required ports for Steam operation - please consult your network administrator to ensure the required ports are open if you are using a university/business network or a proxy. 

Ports required for Steam can not be re-mapped to HTTP or reconfigured to a custom port range.

For generic Steam HTTP/HTTPS requests, your proxy should allow the following domains:

steampowered.com

steamcommunity.com

steamgames.com

steamusercontent.com

steamcontent.com

steamstatic.com

akamaihd.net

Most of the non-web traffic is usually UDP but can be TCP as well. For that, the IPs will all be from the Valve network (AS32590), and a list of those IP blocks can be found here:

IPv4

IPv6