I am using T-Mobile Home Internet and having issues.  pings are around 60 to 80ms  , speeds are 240 but sometimes are much slower,  tv streaming is studdering.  T-Mobile is sending MTU at 1420 instead of Defaut 1500.  I did tr and change the internet MTU but made no difference.  is there another place to change or any idea on how to correct?

Thank You