I mainly watch the local TV channels and until last week, could do this perfectly satisfactorily using a VTV connected via wifi. After VTV was turned off, I have tried streaming the local channels via their apps on my Apple TV which is also connected via wifi. However, the video is very poor quality. This is especially the case for TV3 which is now so horrid that I consider it unwatchable. It's as if the video output has been created by someone using a very wide paint brush so there is no subtelty. This particularly affects skin tones but is not limited to those. 

I don't know if anyone ever gets good quality pictures from live TV via either the TVNZ+ or ThreeNow apps. 

A speedtest on the Apple TV shows the download speed is 230 Mbps. I understand that you only need 10 Mbps for streaming. 

My Apple TV is 4th generation HD with 1080 resolution.
 
I don't know what to do to improve the quality assuming that it can be improved rather than just being a limitation of streaming live TV via apps. I am happy to spend some money but would first like to be reasonably confident that it will solve the problem. 

Some options that I am considering:
1. Upgrading to the latest Apple 4K TV which I understand has better video quality.
2. Using a Powerlink-type adaptor so I can connect the Apple TV to ethernet via gadgets plugged into powerpoints.
3. Getting a Wifi extender.
4. Getting a different streaming device (eg Google chromecast/TV).
5. Trying yet another HDMI cable. (I have already tried 2.)
6. Installing a terrestrial aerial. (I really, really do not want to do this.)

Given that the video quality was fine when using the VTV connected to Wifi, I am inclined to think that it's not a problem with the Wifi but maybe I am wrong.

Can anyone suggest anything? Has anyone had a similar experience and managed to find a solution?

Thanks in advance.