Tangentially related...The December release of MacOS has totally hosed my WiFi connectivity. It stop soon working 2 to 4 tiimes our hour now after being solid since I bought this machine about 3 or 4 years ago.
The irony is that I bought my current MacBook Pro because the last one (ca 2008) ha don’t such horrible WiFi problems that it was unusable.
Now my new machine is as bad as the one it replaced.
I’m not alone, either. Google “Mac High Sierra WiFi” and you will find this is widespread. The proposed fixes are the exact same ones that were suggested four years ago and didn’t work then. Apple is really incompetent at WiFi implementation.
What’s your Wifi router?
Sorry to hear about your problems. I have an old iMac that can’t be updated any further than it already has been. I also have a 2011 MacBookPro that has 10.9.5 on it. I’ve never updated it any further because this has worked fine for what I do with it. I don’t plan on updating it either, because whenever I’ve updated the OS in the past, something has always been screwed up, and I’m not about to deal with that kind of crap at this point in my life.
Are you using 802.1ac or 802.1.g?
Mine has been working flawless on 802.1ac