And when all else fails, unplug the network cable. I’ve had to do that many times.
Yup. I have fixed more problems through the years by just unplugging the computer power cord, or the modem cable power, or the router power and waiting at least 30 seconds before plugging back in. Sometimes it's not enough to re-boot or power down. Being a non-techi, I have no idea why that works but it always does.
When in doubt...pull it out.