@Hirokazu-Tei So you have two Omegas, one of them Omega2 with a fairly old v0.1.5-b130 FW and its Internet connection works sometimes.
These are the latest FWs in http://repo.onion.io/omega2/images/with the MediaTek WiFi driver v0.1.10-b160 with the new Warp Core WiFi driver v0.2.0-b192
Try to download one of them directly to your Omega2 and install it - for example:
(or try to copy the downloaded file from your desktop to the /tmp dir of your Omega2)
BTW What type of dock and extension do you have please?