We really need to see a diagram to be sure. But generally, POE means Point Of Entry which is the box outside your house, or, in the case of an antenna, at the antenna. The filter's main purpose is to keep Moca signals inside your home and off the air waves or the cable company's network. Its secondary purpose is to properly reflect Moca frequencies which slightly improves performance.
I'm having a hard time understanding why you'd have Moca signals on BOTH your antenna's coax AND your cable/internet provider's coax. It should be one or the other. Mixing antenna and cable on the same wire isn't going to work anyway.
My guess is, you don't have any Moca on your internet provider coax, hence don't need a filter. But if you did, it belongs on the line coming from the street. You can keep the one on your antenna feed, but I personally just use a diplexer instead of a filter. It doesn't quite meet the spec but is good enough in the real world, about 99% power reduction.
The only exception to this is tuning adapters. Those may need an additional filter on their input if they can't tolerate Moca signals. Since you're an antenna user, this isn't a concern for you at all.