If Verizon is your Internet provider I'm guessing that means it is a 4g cellular internet box. Technically it is fast enough to stream video, realistically you will probably get what you are describing, which is buffering. If other devices such as computers and cell phones are hooked up to the device through WiFi the speed it provides might not be able to keep up with a full length video stream.
Are you in the city close to a Cell tower? If you are connected to this device on your computer as well try this:
Use google to search speedtest google
View attachment 1715261635
It will start testing automatically. It will tell you if yours is fast enough to stream video.
View attachment 1715261634
