You can’t. the firmware is part of the provisioning from the ISP and not user updateable on modem/router combo devices. 

What ISP? My ISP is GO and they have completely different modems/routers. I bought it by myself on amazon.

Then there won’t be any upgrades to the firmware. Thats the problem with modem/router combo devices and one of the reasons more advanced users recommend buying the modem separate. 

ARRIS supports only the retail products that are available on surfboard.com but not the ISP lease products. Please contact your ISP for further assistance.

It is a great pity that the moderators of this forum don’t read previous posts in the thread. I wrote that my ISP does not use this junk.

Ok, I’m almost there, can you please tell me what is the newest version of firmware, regarding this:
 

Software Image Name: AR01.04.070.09_021522_7246.SIP.10.X1

Firmware Version: 01.04.070.09.EURO.SIP

Thanks in advance!