Airties 4920 with pre firmware from internet suppliere

[Bimha]

I have 2 Airties 4920 with pre firmware only working with my former internet supplier.

1: Not able to login with default gateway ip ( Not able to look up the ip)
2: When setting up them to former suppliers network, using an app from supplier.

So my question is, is there any way to flash the firmware to factory firmware with any tool via network cable, SSH or ??

Br Bimha