As I’m unlikely to be expanding my requirement for PoE retro-fitting beyond VoIP resilience, the learning curve to get my head round all that looks a bit steep. Sticking with a box with a voltage selector like the TREDNET TPE-104GS is probably my safest option.
Having said that, the TREDNET TPE-104GS was bought to include a future upgrade to FTTP in the VoIP resilience plan. I’m in UK & I understand that a BT ONT needs 12v 0.5A so basically max use 6W. The TPE-104GS is rated at 12 V (1.2 A), so enough for a fail-safe solution for the intended ONT, but not for the TP-Link EX230V — nominally 1.5A at 12V = 18W. If I want a simple fail-safe solution for a router, I’ll need to look for a different switched splitter box with a higher output, like the D-Link DPE-301GI, which I think is has a switched user select for 12V output and is rated at 30W, giving a nominal 2.5A for a router.
At least with all you guys filling in the blanks for me, I now have a better idea of what to look for next.