That’s interesting.  My home has all double pane windows and they don’t seem to cause any problems.  My signal is almost always 3-bar good, except for when it goes to 4 bars for a short while.  The thing is 4 bars always means I am having interent connection problems, or my speed has gone too low. Have you tried relocating your tower?  Mine is no more than a foot away from an upstairs window.

My place is stone throw away from the beach. I walked everyday & bike. Every time I do my routine exercise, I have to go or   stop where signal is available for me to call. I look the bar signal & its 5G! Tnx 

Simple solution.  Go back to single pane glass windows.  Certain types of windows can reduce or block cellular signals.  Obviously double pane leads to a thicker window.  Mesh, glazing, and chemicals that can reduce light coming through will also help degrade cellular signal.

“Simple solution.  Go back to single pane glass windows.”  IMHO it will simpler (and cheaper) to keep the double pane windows and have only two bars.