I found some clues. Today I hook up VIM at another place, connect to another WIFI and it worked fine. Here is my network map, all are wireless:
internet <-> router A (dhcp) <-> router B (dhcp) <-> router C (no dhcp, bridge to B)
- When I connect to router C (dhcp via router B): only stock Android can connect to the internet, LibreELEC can not.
- When I connect to router B: all can connect to the internet, both Android and LibreELEC.
- IP on both B or C are the same which is offered by router B.
Both router B and router C are connectable and usable by other devices than VIM, such as ps3, smartphone, smarttv...