The specs for the new version of GL-MT300N do not mention if PoE was kept.
I swear I searched, but then found MT300N-V2 without POE ? where GLiNet declined to develop the PoE module for the mt300n-v2. Oh well.
There is no PoE support in mt300n-v2 because the PCB space limitations.
…and it’s very sad … but true …
I use this POE injector/splitter combo to power my MT300N-V2.