Flex freezing up little rotating circle onscreen

Yes, I have 600mbps superfast plan and a compatible Arris G36 4Gbps wifi 2 in 1 router/modem.  It started gradually, but has progressed to where every single movie I try to watch on prime, YouTube, paramount plus, disney, or other,  will suddenly freeze, and display the loading circle animation. This started even before I changed to a new upgraded modem this past week.  I have new premium cable from the new Comcast service box outside into the modem inside,  about a 25 foot run.  There's no issue with the cable.  I can rewind just a tiny bit,  and the movie will continue,  but I have to keep doing this,  usually 4-5 times in a single movie.  Any ideas as to what is happening? Sometimes it will stop completely,  and the only thing to fix it is to unplug the power to the flex box, wait a few seconds then plug it in and wait until it goes thru all the start up process again.   Please help. Thanks!