120 sec timeout at startup of the WiFi-only laptop when the Ubuntu Server 20.04 is installed.
After greping and reading a bit Ubuntu documentation ... a Quick And Dirty solution found.
Precise startup scripts are disturbed probably. But works on a simple laptop. Don't use it on a serious system.
Don't know what has been changed exactly. It just works.
/usr/lib/systemd/system/systemd-networkd-wait-online.service
Added line TimeoutSec=15s at the end of the [Service] section.
... [Service] Type=oneshot ExecStart=/lib/systemd/systemd-networkd-wait-online RemainAfterExit=yes TimeoutSec=15s ...