Weird, trying another browser probably won't help then (not that Steam should affect them anyways). Hope you get it working, good luck!
Things I have learnt in my attempts so far.
Connection works okay
until I actually load a game, Civ5/Steam does not block the connection when running, or during the time that the intro screen plays, only when the game is loaded.
I am going to try the following and will then update this post
1 Surfing web on laptop when Civ5 playing on desktop.
Laptop, which is on a separate wireless network connection (both are on draft n) to the desktop appears to work fine.
2 Surfing web with a new rather than loaded game, no difference and oddly if I then go back to the main Civ5 main menu, I still can't connect to the internet. I receive this message:
'This web page is not available.
The web page at
http://forums.civfanatics.com/showpost.php?p=8978983&postcount=48 might be temporarily down or it may have moved permanently to a new web address.'
3 Remove Steam from my AVG permissions and then add it again
Made no difference
4 Disable AVG- not my favoured option
Made no difference
5 I also set this lot in my router, even though it was already allowing steam through.
Which ports do I need to open on my router or firewall for Steam? ANSWER:Your network must be configured to allow Steam access to the following ports (in order from highest to lowest priority for QoS users):
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 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)
One other thing, I don't think that it's actually preventing me connecting to the internet, it's preventing browsers connecting to my router. If I have a connection when I start the game, then the connection shows up as okay. If I disconnect then it won't let me reconnect.