I have an amazon firestick on one tv up stairs that’s running about 40-60 mbps on WiFi and I have my Shield hardwired to the same router and running at 150 mbps but it is buffering quite a bit. I have the same apps on both. I’ve cleared the caches and stopped all other apps. I have the same IPTV service and am using the same players. I can start watching something on the shield and it will buffer all the time. I can stop and go right to the tv with the firestick and watch the exact same thing all the way through with no buffering at all. I’m not the techiest person so does anyone have any ideas as to why this could be?
Start by running Analiti on both devices. Run it at the same time.
Might be a dodgy cable, have you tried the Shield on wifi?