"The Wi-Fi network "..." could not be joined" problem again

I'm posting this update to see if it stirs any new solutions or responses. I am running into a network connectivity problem that has been occurring repeatedly - my machine won't connect to certain networks, and I get this error.

Here are some details and facts to narrow down any responses:

- Brand new Macbook Pro, running Sierra 10.12.6.

- It only happens with this machine. I have numerous other devices that connect without issue, as has my last macbook pro before I "upgraded" to this new machine late 2017.

- I've run network diagnostics and it reveals nothing.

- It has nothing to with restarting the machine, caps lock, being near the router, any of the basic advice out there.

- An Apple support tech walked me through reinstalling the OS, which worked temporarily.

I have seen this problem posted around without any reliable and effective solutions, all indications are that it seems to be a deep error in the operating system. And it's quite ridiculous frankly - a top of the line new Macbook Pro having basic and random network connectivity problems like this.

Does anyone have any knowledge of this issue or any solutions? Thank you.