I have no understanding as for the difference between reboot and shutdown-boot cycle. However started recently I have this weird problem that I have no internet if I cold boot the machine. I have to use reboot to have internet again.
During the disconnected state, I can only ping my router. But ping 188.8.131.52 gives “network unreachable” reply in console.
A multitude of possible causes for your described problem but maybe the best place to start is your Gateway device(assuming this is a SOHO Workgroup scenario using an inexpensive home gateway device).
My guess is that your machine may be announcing, but is not being recognized by your Gateway device. Don’t clear the settings, but clear the stored data like DHCP cache, thereby forcing all devices on your network to re-register. Sometimes simply rebooting the Gateway device effectively clears the data.