2 tvs 2 different problems

TCL Roku 75r635 -high speed wifi. Fast forward recording when stopped buffers, thank u for patience then returns to starting point

Roku 55r6ax hard wired to internet - slow to load tiles and library, fast forward preview disappears making impossible to tell where to stop. When stopped, recording plays normally.

Directtv says probably internet problem. WOW internet service home visit says everything good. Speed close to 600mbps