MacBookPro connects to the internet only in Safe Mode

It all started yesterday, Tuesday, 23 June 2020, when I turned on my computer to find out that I could not connect to the internet, although the Wi-Fi was green on the Network window, and the IP address was showing. I used my old computer, running Windows, to watch numerous videos on Youtube with suggestions about how to solve the problem. None worked, except one which advised me to restart on Safe Mode. In addition. Following another suggestion, I downloaded (in safe mode) the Etrecheck software from the Apple Store and ran it in normal mode. Then I emailed the diagnostic test to Etresoft in Canada. A very kind man, John, advised me the next morning to remove TunnelBlick. I did so and internet connection was established in normal mode. But it was interrupted again in about an hour. Back to square one again.

I have the Dianostic report, but I don't know how to communicate it here.

Anyone can help?