Dedoimedo published a quick tutorial showing how to troubleshooting unusual Linux network connectivity issues.

Linux networking - A weird little problem with DNS, DHCP

Short tutorial showing to how troubleshooting unusual Linux network connectivity issues due to misconfigured leftover DHCP IP address assignment from a software installation, with a step-by-step approach covering Wireless and wired networks, different network ranges, routing table, DNS, Systemd resolve, Network Manager, and more.

Linux networking - A weird little problem with DNS, DHCP