Hi,
thanks for the help - managed to fix it.
First, "Could Not Connect to the Server" problem:
My antivirus - NOD32 was to blame. I had previously added GT Legends to every possible exception list, but the antivirus "forgot" that.
Second, having to enter the serial every time:
Steam is to blame - the serial is stored in the registry, and Steam modifies it every time the game is started, adding "-" to it. So I went inside regedit and modified the permissions for the keys, so Steam cannot modify it.
Here's how:
(1) When you start up the game, at the Main Menu, click on "Multiplayer"
(2) Now click on "Internet"
(3) Click on "Register"
(4) It will now ask you to create the following - Username, password, confirm password, and email address. Go ahead and enter these, and click on the arrow to proceed. It displays the message "Please wait".
(5) You'll get the message "Invalid Key". Ignore that and now enter your login details (username, password) that you just created. It will eventually come back again with "Invalid Key". Now, go back to the Main Menu.
(6) Click on "Multiplayer" again
(7) Click on "Internet" again
(8) Now, it will ask you for the serial number. Enter the CD key as given you when you either start the game through Steam or click on the "CD Key" option on the right of the game's page in your library. Enter the key using CAPS for the letter, with NO hyphens (dashes) between them.
(9) Now attempt to log in again. After the "Please Wait" message it should be successful and bring up the multiplayer screen/server listing, etc.
(10) If it still comes back with "Invalid Key", repeat from step 1 again. DON'T try from step 6, as the game will not ask you for a key.
I found this solution on the steam forum
here.
I am using Windows 7 64 Ultimate with Service Pack 1, and my rig is an i7 4820 with 32 GB ram, AMD Graphics R9270X, and I'm running GTL off an external eSata HDD.
I posted this in case somebody else has the same problems.