TV loses connection

[#1]

Hi. I have an old smart TV and BT youview box. They are in the same room as the router and attached by ethernet cable. I am constantly getting a pop up saying 'Can't detect your broadband' followed a minute later by, internet restored. It's only a problem if watching I player or similar because it stops/ buffers or even loses the programme.
I had the same problem with my previous provider Cuckoo, which is why I switched providers.
Is it my TV or Youview box? Or the connection into the house which Plusnet did not change?
I have checked ethernet connection.
Laptop and phones don't seem to have any problem.
Would love some advice before I shell out for a new TV.

[#2]

@JH98 From your comments above, I would be suspecting either the YV  box or your TV, but beyond that I would not like to speculate.

[#3]

ethernet cable faults often look like an intermittent connection

[#4]

@JH98    As @PhilipHeyes says have you tried changing the ethernet cables between the router and TV/YouView box..?  Cheaper to try that first before assuming you need a new TV....  also worth changing the ports used on the router just in case of damage to the connectors...

[#5]

Thanks I will try a new cable and let you know.

[#6]

@JH98 

You say you have a smart TV and a BT youview box. Are these two separate items, each with their own Ethernet cable or is the TV getting its streaming services through the BT box, rather than using its own smart features?

Can you confirm that you have a Full Fibre connection, not something slower?  What speed are you getting with a wired connection to the laptop?