at first, thanks Opera for the new feature of VPN in Opera developer 38.0.2205.0.

unfortunately, after enabling VPN in settings, a VPN button is shown in the address bar and it is always yellow, not blue.

the information in the VPN dialogue shows the switch is turned on and the state is Connecting.
there is no Virtual location in the list.

how could I solve it?

by adding some particular hostname and IPs in my hosts file?