1. Switched off and on the TV unplugged etc
2. Done the same for router
3. Deleted samsung account and reinstalled
4. Deleted and reinstalled amazon prime
5. I have 150mbps speed.
6. All other apps working
What's the solution
I live in New Zealand and experiencing the same issues, I have tried all the suggestions here to no avail. Today I had an on line ‘chat’ with Samsung NZ and they said they had no knowledge of the issue, I forwarded them this link and was told US televisions have different software, I replied that whilst I appreciated this I was getting exactly the same issues with a notification of insufficient bandwidth. After a fruitless conversation where I reiterated all other television apps were working perfectly and I had also carried out a total reset, plus Prime Video is working perfectly on all other devises I surrendered as he could offer no further help. Frustrating!
OK so the below worked for me, my device wasnt registered so couldn't deregister it just had a Prime app screen saying wasnt connected to internet.
I went into samsung tv network settings and disconnected my wireless internet connection from my TV.
I then reconnected my internet back to TV and when I tried the Prime App it worked
I am in the US.
I have a Q8 Series (65). This morning I attempted to load Prime. Prime attempted to log on--quickly flashed and then would not respond to my attempts to reload. I reset the Smart Hub and reinstalled the Prime app. No change. The TV did not show as a device on my Prime account. So I disconnected my WIFI. Reconnected the WIFI. No change. I then turned the tv off for a few minutes. Once turned back on the Prime Video app responded and landed me on the sign in/register device screen.
very strange but it is working now.
I tried deauthorizing my device but it wasn't listed on my authorized devices anyway. I followed the tested and true 1st rule of troubleshooting... Unplug it and plug it back in after a minute. Then hold the power button down for about 20 seconds till it recycles. Amazon started up just fine after that.