R6020 (AC750) - bridge mode not available

Netgear R6020 (AC750), quick $30 Walmart pickup to fix easy problem at in-laws' lake house -- wired-only device needs access to wireless network in other building.

V1.0.0.14 firmware

Apparently, I misread the docs before purchasing, but I don't see any way to enable bridge mode on the R6020.  Am I missing something?  Alternatively, is there a compatible DD-WRT build?  This is simple functionality.

Thanks much.