Comcast appears to be throttling connections from my cell phone

It appears that Comcast (my ISP provider) is throttling connections only from our cell phones. Everything else appears to connect OK (not great but adequate.) If I try to click on a link that somebody sends me or perform an internet search it can take several minutes to bring back results. Sometimes it just cancels out. This is happening for both my wife and I, and we are on different types of cell phones with different providers. If I perform the same search on a laptop I get normal results -- within a second or so.

I've unplugged my router and powered it down several times, but that doesn't help the problem. Is it even possible to throttle connections from certain devices? Has anybody else experienced this problem?