For weeks I've been having major problems with Google Chrome on MacOS, which would constantly get stuck on Resolving Host and fail to load pages. Firefox would load the same pages without a problem.
I kept searching for the problem and doing all the fixes people recommended for that error, all to no avail. I wiped out my Chrome settings, troubleshooted extensions, reinstalled the app, etc. Nothing worked.
I got closer to figuring out the problem when I tried to change my DNS addresses. I changed them on my router/DHCP server, renewed my leases (the Mac has dual ethernet ports) and they would change to my new DNS addresses, then change back to some unfamiliar addresses within seconds. I kept going back to the router, trying to figure out where these addresses were coming from. Couldn't find anything there. I overwrote the DNS servers on the computer; they would still change to these suspect addresses. I even turned off DHCP and set my IP settings manually. STILL they changed to these other servers.
This seemed like malware/virus like behavior, so I downloaded and ran Malwarebytes. No malware.
By this point, I'd spent hours trying to figure this out. I was about to reinstall my OS, which would have cost me a couple days worth of work and STILL wouldn't have resolved this. Then I had the idea to search for these DNS servers and at least see if other people were dealing with this. One of the first results mentioned DYNDNS. Sure enough, it was the "Use Dyn Recursive DNS servers on this machine."
I do not remember ever setting this myself or allowing this setting.
Pretty furious that this stupid setting would overwrite even manual IP settings, especially when it probably only exists to provide Dyn with usage info.