Hi - Thanks for your answer here - I'm also looking at using POE adapters from Ubiquiti. The product mentioned above (POE-24-24W) suggests that it is not gigabit ready and will fall back to 100 Mb/s speeds. also based on the chart here: https://dl.ubnt.com/datasheets/poe/PoE_Adapters_DS.pdf
However, I have a couple of the POE-48-24W-G models (48V +4,5 / -7,8) lying around from previous Ubiquiti purchases and they seem to suggest they are Gigabit ready (something to do with using center-tapped transformers to pick off/add the voltage bias but I'm no engineer so I'm not sure exactly how it works)
The Teltonika documentation mentions specifically "10/100 mode B, DC on spares" but I'm not sure whether that excludes it enabling gigbit speeds even with a gigabit enabled PoE injector.
this page: https://planetechusa.com/power-over-ethernet-poe-demystifying-mode-a-and-mode-b/ tries to explain Mode B with relation to gigabit
I can't be sure whether that means Teltonika supports the configuration in the rightmost column as it isn't mentioned in the documented pinout table: https://wiki.teltonika-networks.com/view/RUTX08_Powering_Options#Passive_PoE
it's perhaps a moot point as I'm unlikely to get more that 100 Mb/s from the 4G signal at the moment, but as they add more LTE-A towers around my house the theoretical maximum throughput could put it above 100 MB/s.
Many Thanks!