The opinion about correct Ports for steam and the games within

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I researched and discussed about these correct ports to forward my router and computer, a lot of people have their own opinion about this. I was sure the people who is working with Valve/Steam know what they are talking about, but not everyone did agree with that. This is what I learned:

Steam says this:

Steam Client
UDP 27000 to 27015 inclusive (Game client traffic)
UDP 27015 to 27030 inclusive (Typically Matchmaking and HLTV)
TCP 27014 to 27050 inclusive (Steam downloads)
UDP 27031 and 27036 (incoming, for In-Home Streaming)
TCP 27036 and 27037 (incoming, for In-Home Streaming)
UDP 4380

Dedicated or Listen Servers
TCP 27015 (SRCDS Rcon port)

Steamworks P2P Networking and Steam Voice Chat
UDP 3478 (Outbound)
UDP 4379 (Outbound)
UDP 4380 (Outbound)

Additional Ports for Call of Duty: Modern Warfare 2 Multiplayer
UDP 1500 (outbound)
UDP 3005 (outbound)
UDP 3101 (outbound)
UDP 28960

Portforward.com has this to say:

Steam_Client
TCP/UDP - 3478 (Translate to)
TCP/UDP - 4379-4380
TCP/UDP - 27000-27050

Steam_Server
TCP/UDP - 27015 (Translate to)

Counter Strike
TCP/UDP - 1200 (Translate to)
TCP/UDP - 27000-27015
TCP/UDP - 27020-27039

Counter Strike Source
TCP/UDP - 1200 (Translate to)
TCP/UDP - 3478 (Translate to)
TCP/UDP - 4379-4380
TCP/UDP - 27000-27050

Counter Strike GO
TCP/UDP - 3478 (Translate to)
TCP/UDP - 4379-4380
TCP/UDP - 27000-27050

The Secret World
TCP/UDP - 80 (Translate to)
TCP/UDP - 7000-7999
TCP/UDP - 6881-6889

Different individuals around the internet:

Random guy from forum:
UDP 1200 (used for friends service)
UDP 27000 to 27015 inclusive
TCP 27020 to 27039 inclusive
TCP 27040 and 27041 only for CyberCafe Owners

Computers running Dedicated Servers need these ports open:
UDP: 27015 and 27020 (default HLDS, SRCDS and HLTV port)
TCP: 27015 (SRCDS Rcon port)

Ronimo Maarten:
In the meantime you could open the following ports on your router to get a better connection to Steam:
UDP 27000 to 27015 inclusive (Game client traffic)
UDP 4380

Youtube guy - AbsMayhem:
open ports TCP 27000-27050

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So the question remains; What is actually the correct Ports to use?

Shouldnt Steam's own information be regarded the most trustworthy and correct info? They are after all the ones who own and control this whole network..

Just got me thinking, and I have read a lot of information these last few days, I have the usual steam bug "Connection Lost" so will actully port forwarding help with anything? Thought UPnP did all this for me?