A very annoying problem came back to a Xubuntu 14.04 (Trusty Tahr) system quite suddenly and annoyingly would not go away. This system would not obtain a DHCP address. The Network Manager tray icon was not even the "spinning" icon indicating it was trying to obtain an address from the DHCP server. I checked around the Internet for suggestions how to resolve this issue. Nothing we located and tested resolved the issue.