Test all devices that are using the router

[VitiLevu1]

My Amazon fire stick 4k max apparently has too much of an upload and download appetite causing buffering and screen freezing. Router has been restarted also reset, unused Wi-Fi devices have been turned off. Still a problem. Spoke to Talktalk tec and they said they’d fixed it, but hadn’t.  
How do I check what devices are drawing Wi-Fi from the router and their condition?

How do I stop this damn buffering and screen freezing?

[Debbie-TalkTalk]

Hi VitiLevu1

What speed are you receiving?

Please can you add your name and TalkTalk landline number to your Community Profile.

Thanks

Debbie

[ferguson]

Amazon Prime 4K Video does require a minimum of 15 Mbps download speed, more is obviously desirable if you are intending to use other devices at the same time. What is your broadband speed generally?