Ubuntu kernel 6.8.0-100-generic has buggy networking

Some wee debugging ere the weekend. A tutorial on how to resolve intermittent networking problems in Ubuntu with the kernel 6.8.0-100-generic, including overview of the issue with Web pages not loading, apt repositories not reachable or ping command failing, workaround by booting into an older kernel, how to edit and update the GRUB menu style and timeout, and more. Take a look.