Porting 5060?

Hi, There I got 2 Tenda routers. An F9 and an AC10. I do experience the following problems on both of them. When streaming from them and they are both on a Fibre network it starts stop streaming after a 3-4 hour session. My system seems to start buffering. Normally I switch them off and on and wella no problem for the next 3-4 hours. All my systems run on cables, not on WiFi both are set up on defaults setting to give me unlimited throughput. Is there a way to monitor it or a setting to resolve this? My second problem is they are blocking my VOIP port on 5060. Is there new firmware for them because I can't find any on the Tenda website? Any other inputs will be highly appreciated. Best Regards Willie