HBOMax buffering issues

Having HBOMAX buffering problems like everyone else. Happens on our one X1 box.  We access the HBOMAX app using our X15 remote by pressing the Xfinity button on the remote, scrolling right to the Apps option, then scrolling down to the HBOMAX app option.  All other apps and streaming services function properly; the buffering issue happens only on HBOMAX. Box was replaced 2 weeks ago by Xfinity tech, no improvement. Today HBO completely froz while playing ads. Could only fast forward but never got it to play the show. Have done all troubleshooting tips including refreshing box, restarting box as well as restarting router. Nothing helps and happens pretty consistently try out day. Eventually give up because it’s a waste of time.