I connected a 3Com Wireless AP to an existing network (20 users). I was able to connect to the shared Internet almost instantly. 15 minutes later, nobody could get on the Internet. I could still access the network server and shared printers, just not the Internet. I verified that all the connected PCs were configured to automatically receive IP address. I finally disconnected the AP and rebooted the server; DSL modem, router, and all PCs. Everybody could get back onto the Internet. I then connected the AP and everybody could still connect to the Internet. I am afraid the problem will happen again. Any thoughts?
The symptom you describe sounds like the DSL modem/router briefly lost Internet connectivity. Because you could reach other destinations on your wired network (server, printers), you had a solid Ethernet connection from your AP and solid wireless LAN connectivity. The failure had to occur in routing to the Internet, which could either have been a problem in your DSL modem/router or loss of upstream connectivity. Since rebooting your DSL modem/router cured the problem, my vote is loss of Internet connectivity.
If you experience the problem again, look at the status of the DSL modem/router to see what's happening there. See if you can ping the Internet from another PC on your wired LAN, but not from your wireless LAN. Verify that you can ping your AP from your router. Examine the router's routing table and interface status to determine whether the WAN link has gone down or its "WAN IP" DHCP lease has been lost. It's not unusual for Internet connections to experience blips like this, but if outages happened on a regular basis for long periods of time, then I'd look for a possible router malfunction.
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