[SOLVED] TalkTalk router Sagemcom FAST 5364 with Netgear Nighthawk R7000 VPN

[dat789]

So, following my post here, I decided to set up VPN via another router on bill001g's recommendation. I got the Netgear Nighthawk R7000 (AC1900) and received it today.

TL;DR -- Logged on to TT's router admin panel on 192.168.1.1 to install ExpressVPN's firmware onto it. It didn't recognise the file, so unable to do anything.

TalkTalk is my ISP and was provisioned the Sagemcom FAST 5364 Dual band Wireless router (primary router).
On ExpressVPN router setup page, I have downloaded the firmware (a *.chk file).
Mine will be a primary router with the Nighthawk (secondary) set up.
It seems like I have to update the primary router's firmware with ExpressVPN's. I'm having trouble with that and I wonder if anyone here has successfully set this up?

On TT's router admin pages, this is what I've done (in screen shots). Even with the file selected, it says "No file chosen. Please click 'Choose File' button and select a file.

Anyone has any ideas how to configure a dual router VPN set up?

 

[dat789]

Ah! Nevermind the above. I think I figured out and resolved the problem.
It was not clear in the instruction which router to install the firmware on. The firmware downloaded from ExpressVPN was meant to be installed on the Netgear (secondary) router.

Your primary (existing) router will remain as-is.
Power up the Netgear router and plug in the ethernet cable from primary to secondary's Internet port for connectivity.
Then, use one of your devices to connect to the secondary router on Wi-Fi.
Follow through the instructions for setting up.
Install ExpressVPN firmware.

You're done!