TP-Link Media Converter Confusion

For future reference a TP-LINK MC220L has multiple versions. v4 supports fallback to 10/100mb ethernet, whereas v3 ONLY SUPPORTS GIGABIT ETHERNET!!! When connecting to a 10/100 device occasionally I had a brief TP Link light but it would not stay illuminated. But testing against multiple 1000 vs 10/100 devices proves the v3 is only 1000mb.