I have a routing mystery! I have a client that would do a remote mysql database connection to one of my servers to update some sites he has here. The script that updates the databases is on another host. This has been working fine. All of the sudden the connection times out at the router above my servers, which is a cisco 851. So we test the connection on another machine at another ip and it works fine. The server that cannot connect can traceroute to my router and then it times out. So it seems the problem is at the router. However there are no ACL's on the router, in fact the only ACL I have added is to allow that IP. What else could be blocking this connection aide from a router ACL? I am stumped! I can ping the other server from my servers so i can get out of the router to them, but they cannot get in. All other traffic for the several hundred accounts is also running fine on my server. Just this one IP address is suddenly unable to route to my server. Ugh!
Could it be they have a problem with the IP of my router so tcp packets cannot return?
I am out of ideas as to where to look. Any ideas out there?