Cannot sync Google account over wifi, only on mobile data: HTC one Google Edition, T-mobile
I got my HTC One Google edition from google a few months ago but I had to wait until now to switch to T-mobile because of my contract with Verizon. So I have been using my HTC One as a wifi only device until I plugged in the sim card from T-mobile. Right now, I cannot sync my google gmail account whenever I am on wifi and can only do so on mobile data. So I can't use play store and other apps because it just won't sync when on wifi. When I tried to sync manually in Google account under Settings on wifi, the setting page lags a lot, sometimes it can even hang as if attempting to sync is causing some problems. If I switch off wifi and mobile data kicks in, there is no problem syncing and there is no lag on the setting page. Before I plugged in the sim card, there was no problem with syncing over wifi. I even tried to take out the sim card and turn the device back to wifi only and the problem persisted.
I don't think there is a problem with my router (linksys e2500) since my tablet Nexus 7 can sync my google account over the same wifi network. I even tried to use a older router but it still have the same problem. Please help.