Check configuration but first, disconnect your router and plug your box directly to the modem and see if there is any freezing, if so, its not on your end, If there is no freezing, consider reconfiguring your router with a focus on QOS or quality of service for your box which you should set to high with appropriate up and down speed / bandwidth/ This will help prioritize streaming although you could check to make sure media and streaming settings are set if you have them on your router.
