You might have to allow the login with the new IP. Instead of leaving my router on all the time, I shut it off at night, personal reasons. When I do that I get an email from ArenaNet asking me the following:
A log-in attempt from the following location is currently awaiting your authorization.
Address: 000.000.000.000
City: XXXX
Region: XX
Country: US
This location is approximated based on information provided by your Internet Service Provider. If in doubt, deny the request and try again.
If you are certain this log-in attempt was not made by you, then someone else knows your log-in credentials and you should change your password immediately via Account Management.
For security purposes, we alert you each time your account is accessed from an unrecognized location. To authenticate this log-in attempt, please click the link below: (of course I won’t post the link, I think you get the idea 
)
Check your email. I hope this helps, maybe you already knew all this but in any case I hope you get it straightened out.