I've had this problem as well on my Roku ultra with gigabit internet. It only happens on the DTV app.
I FINALLY found a fix!! Maybe this will work for others.
1. Go into the DirectTV app and select any channel to watch.
2. Hit the ✳️ key to display the options side panel, and scroll down to "Volume Mode".
3. Change this to "Leveling" which is supposed to smooth out highs and lows.
After doing this, the volume level really increased but no more intermittent audio skips!!
Hope this helps, spread the word of it does