First change the default gateway IP address back to the address of our router. Changing that IP Address will not speed things up.
Do you have a roaming profile? If so (most companies use them) that is why it takes so long to login. The server and your workstation have to compare all the files in your roaming profile and update the files between the server and your workstation. Reduce the size of your roaming profile by moving files that you don’t need on the server from your profile to another folder on the workstation.
If yoiu are using roaming profiles, then you can often decrease the amount of time that it takes for users to login by using folder redrection.