This age-old problem seems to never go away.
There are thousands of threads related to Wi-Fi dropping constantly. Unfortunately, almost all of them seem to have quick hack suggestions and no real explanation of what the hack actually does, and no detail on how to debug your system to properly determine if this hack is indeed what you should try.
In this question, I am asking for an aggregate guide to properly debug this issue and the solutions to the most common issues.
My goal here is to have a single go-to thread that those with similar issues can walk through and resolve their problems (rather than opening a new question every, single, time).
PS: I was inspired to open this thread when my MacBook Pro suddenly started hanging & dropping wifi every few minutes after either a recent kernel or Broadcom update. Searching found no real solutions and I have yet to resolve it.
Each wireless adapter has a unique solution. Sometimes groups of adapter have similar ones. Dozens of different adapters.
Also there laptop model specific solutions.
In addition could be configuration problems, etc.
A guide that covers all that is possible, but not very useful. People need to solve their own problem, not to have a 100 page book about how all problems can be solved.