Given this particular problem, I wound up putting IP-switched outlets on the AC power adapters for both of my Tablos, allowing me to recycle power/reboot from my iPhone when I am either home or away.
I originally used relatively expensive switches sold by 3GStore.com @ $79 apiece, but I've had equal success with a much less expensive switch is made by Belkin, called "WeMo" for $29 apiece.
Note that remote access, once it has failed, cannot be established remotely, since the iPhone and Tablo need to be connected locally via Wi-Fi/LAN in order to reconnect.
However, Tablos which cannot be found on the network can be rebooted and re--paired locally, restoring proper recording and playback. From remote locations via the WAN, rebooting will restore recording functions but no remote playback.
It sure would be nice to have a login account method of access / re-pairing like Nest, Belkin, Logitech, and most other WAN remote devices.