A "typical" instability

[serge1966]

I just received my first three Wemos Lolin32 boards and tried to load a few sample sketches. The only way I can describe what I see, is instability.
What happens in my case is if I load a simple PWM LED sketch without serial write, it works just fine on all three boards. But when I load a sketch to scan for WiFi networks, I get three different results.
#1. Printed "Setup done" message, which is printed at the end of the setup() function. Nothing printed after that. After I pressed Reset button on the board, I received what is expected from the loop and it looks good.
#2. Did not print anything.
#3. Produced all expected output: message from setup() and then repeating messages from loop()
Then I recalled a video on youtube from a "guy with a Swiss accent" - Introduction into ESP32 (#147) and at 10:39 he speaks about "typical" instability. Do I observe the same typical instability, related to serial print? Is there a good article or discussion on this topic as so far I could not find any?
Also, I often get "port is busy" message during sketch upload and the only way I found so far to work around it is to reinstall the COM driver before each upload.
I was thinking that when a sketch with serial print runs, it communicates through the same port, through which code gets uploaded to the board. Don't these two processes step on each other's toes in the beginning and cause those issues?

One other question is with regards to the driver. I have seen a few references to the CP210x USB to UART Bridge Virtual COM Port (VCP) drivers page, but there are a few options that could apply to my case and I am not sure which one is for my Windows 10:
CP210x Universal Windows Driver
CP210x Windows Drivers
CP210x Windows Drivers with Serial Enumerator

Arduino IDE 1.8.15

Any comments will be highly appreciated.

Note: I have some knowledge of hardware and software design, but little to none practical microcontroller experience.

[mrburnette]

...
#3. Produced all expected output: message from setup() and then repeating messages from loop()
Then I recalled a video on youtube from a "guy with a Swiss accent" - Introduction into ESP32 (#147) and at 10:39 he speaks about "typical" instability. Do I observe the same typical instability, related to serial print?
...

I have done numerous ESP32 (and ESP8266) "under Arduino" projects. As for the ESP32, I have seen no stability issues with Arduino code nor have I seen any "Arduino core" software concerns (outside the list on github.)

The ESP32 projects "demand" a clear build: prototyping boards and pin-jumpers will create a huge mess as the problem is two-fold: jumpers are little antennas that love AC hum and solderless boards and jumpers are often nasty and have resistance and voltage drop. ALL of my prototyping problems have been due to interference or voltage issues with the AC supply (ripple, Vdrop) or similar issues.

Dedicate a set of parts and use a roomy all-sided metal box for an enclosure (Big tin boxes work if you jumper the top lid to the base enclosure and TEST for 0 Ohms between top and all sides!

Do not use a wall wart. Use an inexpensive "lab" DC filtered power supply. IF you utilize fluorescent lighting - do not!

Avoid ground loops... pretend your digital stuff is audio and ground accordingly.

Ray