Apple TV Gray Static Screen - with Noise like Blowing Air Through Teeth

SetUp - LG monitor (42") - apple tv - brand new HDLM cord - 5g 5 bars spectrum cable internet. Had a 4K apple tv (for many years) connected - started going to gray screen every few minutes (with a strange sound) - bought a new HDML (8k) cable - worked on HD (but because my TV does not have dolby video- it was washed out). On SD - continued to go to gray static screen. Changed 4K apple with a much older apple tv (that worked) - used new HDML cable - worked for one day. Today the gray static screen is back about every 10 minutes. Sometimes it switches back on own - other times we have to tun off the tv and turn it back on. Any suggestions?