The issue is resolved. For the benefit of others, let me explain. My entire network/OS/browser did not change when I was getting the service and when I stopped getting espn3 service. It seems if the bandwidth is reduced somehow, error 310 is possible with espn3 video streaming. I'm surprised that neither Charter (support is horrible anyway) nor espn support folks mentioned this fact. So, I tried connecting to the modem directly and the video streaming started working as before. I did not change router/modem/any hardware. It appears that I need to upgrade my bandwidth or find out if there is any bottleneck between my PC and the modem. I do reset my router every once in a while.