Do I have a WNDR3700v1 or WNDR3700v2?

It's a "WNDR3700 N600 Wireless Dual Band Gigabit" router that I've had for a few years, and it works fine.  However, checking for a new version of the firmware always fails ("Please Connect Internet Port and Retry"), probably because I'm using it as an AP, not a router.

I've looked all over the case, but see nothing other than "WNDR3700 N600 Wireless Dual Band Gigabit".  Not even a serial number.

Thanks.