Believe or not
1, Unplug the LAN cable which is connecting switch from the Modem. Wait for 1s.
2, Unplug the LAN cable which is connecting switch from the PC. Wait for 1s.
3, Plug-in the LAN cable from switch to PC. Wait for 1s.
4, Plug-in the LAN cable from switch to router. Wait for 1s.
5, Solved until next restart :-)
Gosh