With the new profile working fine and as expected you have proven that your Mac has no issues and it is no Apple bug. So far, so good.
There is no easy way here. There are two different options how to move forward:
- Get rid of third-party stuff in your everyday profile dealing with mounting drives, energy saving and what not until the issue hopefully disappears. And if it disappears at one point and you do need the app you have just removed, try adding it back (if needed) and see, if the issue is coming back. And then deal with the app (or consider getting rid of it permanently).
or
- Keep adding stuff to the new profile until you are back and running everything you need without issues. If the issue is coming back, debug the app you have added most recently.
The thing with both options is that it is time-consuming, both have their advantages and their disadvantages. It takes a lot of time to change stuff (no matter if removing or adding) because you always will have to check, if the issue has gone away (after removing something) or if the issue has popped up (when adding stuff). Only a few days ago I linked to Allison Sheridan’s debugging of her battery drainage issue that has been ongoing for years. She still has not 100% proven what was going on - after a lot of hassle.
Your issue is not as bad because a simple new profile already solved your problem. But still, debugging is time-consuming.
That is the more global view.
Regarding your disconnection problems: I have no idea, but I got to thinking when I read about sleepaid, sleep settings in terminal, amphetamine and what not. Try to get rid of individual stuff messing with the mentioned areas and hope that it eventually goes away. You are not alone with the issue you have mentioned, there can be so many causes. Or try to make the new profile your everyday profile eventually by adding stuff you need one by one (second option) - with patience because you want to make sure that you identify the cause of your problems successfully in order to get rid of them when you are adding apps/changing settings.
I know, not helpful, but I have no better idea. Maybe, somebody else does have one. 