Suddenly Can't Connect to Internet Through D-Link Router

[jammasterj]

I have a D-Link router with a 4-port switch and an integrated wi-fi access point. It had been working perfectly for about a year. One day, I couldn't access the internet through any connection, wired or wireless. I exhaustively when through every router setting, but nothing worked. I decided to connect my XP computer directly to the incoming line (apartments are connected to a T1). At first, that didn't work either. But after waiting a little while and trying again, I was then able to connect. However, whenever I disconnect the line from my computer (i.e. to test the router connection again) and then later reconnect it, it never immediately works. I have to wait some random amount of time (i.e. 1 hour, 3 hours) before it will connect again. The ISP that hosts the T1 says that they haven't changed anything, and I've spoke to them numerous times without accomplishing anything. I'm by no means a novice in the networking arena, but this situation has me pulling my hair out. I just hope somebody has some ideas.

 

[MichaelDell]

Clarify what you mean by connect. Are you getting an IP address via DHCP or they statically assigned?

 

[jammasterj]

The WAN address from the ISP is static. The addresses on my local network (behind my router) are DHCP.

 

[MichaelDell]

Any messages in the Event Viewer under System during the time periods where it cannot connect on the XP machine?

What happens when you try to ping your way out when you just have the XP connected? Example:
Ping localhost - What is the result? If good,
Ping the gateway IP - What is the result? If good,
Ping the ISP's DNS servers by IP. If good,
Ping the ISP's DNS servers with ping -a x.x.x.x. Does this resolve to a FQDN?

How does the ISP authenticate you, or do they do any authentication at all? Is it by MAC address?

I would try to get as much info out of the ISP regarding how they authenticate and how their system works.