Cool. You're looking for a 'jump box'/'bastion host' then. I'd go with the Certa. That microSD card slot is just what's needed to expand its attached storage beyond a partly 16 MB. I've written a script so you can link opkg install packages to it without risk to breaking the native GL firmware. It should work on the Shadow too but the Certa has a uSD slot and a USB port. I'd use the USB port for dumping packet capture files to it should you ever need to. See below: