Why does Apple Watch disconnect from external Heart Rate monitors?

I have now had two (2) Polar H10 Heart Rate monitors. Both disconnect throughout a run. Perhaps every 5 minutes or so. I don't have the bluetooth on with the phone and I do not carry the phone with me. Given how infuriating this was, I purchased a Garmin HR monitor to see if that was any better. Nope. That drops every few minutes or so.

This was a problem with the iWatch 3. So... I upgraded to the iWatch 7. Same problem.

This leads me to conclude, with some certainty, that the problem, exists with the iWatch series.

Given that the watch is literally 5cm away from the unit when I run - I cannot conclude that it is "too far aware." Given that there were two separate brands - I can't conclude this is a HR firmware problem (which is up to date on both types of sensors).

Apple... you got to fix the stuff!

[Re-Titled by Moderator]