Sky puck keeps glitching and blacking out

[Zara2]

My sky puck keeps glitching out every 20 seconds and the screen keeps going black, it's not my tv as works fine when not using the Sky puck 

[lettice]

Younqhve not mentions if this a new puck or an existing one.

This sounds like a local network issue or some interference for the puck.
Having a good local network is a key factor for having a reliable experience with Sky Stream.

A recent change in your local network may also affect how the ouck performs.

Best way to test is via a network speed test on your Puck.
Launch Netflix on your pucks (you do not need to be logged into it, if you do not use netflix) and scroll down the left menu to Get help.
Choose Check Network.
Would suggest running the test a few times, over say a half hour period during tests or at the busiest times of your household internet use.
What is your speed for your. puck?

Also, it may be suffering from interference, more often seen as an intermittent blip.
Not always a cure, but the following may help to resolve;
Make sure you have a good 6-8 inches free on all sides of the puck.
Do not stack the puck on top of any other device.
Make sure the puck is in the open, not tucked away in a cabinet or sat directly behind the TV.
Make sure you have no other devices that can cause interference closeby, like cordless phones, radiators, baby monitors, smart meter in home displays, microwaves and the like.

Plus, change both your pucks to following recommended settings set in Settings>
Set Network standby mode to ON and turn  wifi OFF under Network if connected via ethernet.