One day, I had an event occur where my gateway (router) mysteriously rebooted itself. Ever since then, when I try to access any website, it takes a very long time to connect. Once the initial page loads, I can click around to various parts of the website and they load quickly, but the initial connection to any address takes forever. Once I stop accessing the website for about 5 minutes and then go back to it, the lag returns. Even on a site to which I have already established a connection, images will often not load for a long time.
This only happens on my desktop. Other devices are not affected. Tablets, phones, and a laptop are all using the same gateway without any issues. I have conducted an internet speed test on the desktop, and it registers at 50 Mbps, which should be more than adequate. The same results occur on Firefox, IE, and Chrome. Windows' "troubleshoot problems" wizard returns no issues.
I have tried both a wired ethernet connection and a wireless connection to the gateway with the same results. I uninstalled my antivirus, but there was no change. I cannot do a system restore as this occurred on 12/10 and any restore points from that long ago are no longer available.
Update: I ran the "troubleshoot problems" wizard again and it returned the following message: "Your computer appears to be correctly configured, but the device or resource (DNS server) is not responding." I went to the website for my ISP (Comcast) and I was able to reset the router from there (not a reset to where it changed the password or anything; it seemed more like just a restart), and the internet connection was super fast and perfect. I ran the "troubleshoot problems" wizard and it didn't pick up any problems.
After about 5 minutes, it started going slowly again, and now the "troubleshoot problems" wizard is returning the same message.
What can I do to fix this?