I have a PLEX PX-W3U4, connected to a Linux PC running KonomiTV. When I moved into my new apartment, I realized that various local terrestrial digital channels, like Tokyo MX 1, Tokyo MX 2, and NTV had reception issues. It turns out that this was easily resolved by reducing the signal using a -15 db attenuator, because apparently it's quite common for the singal to be too strong(?). I was really skeptical this would work, but it did.
I'm using a particular mirakc konomitv setup. In b25, I'm using a modified start script that runs b25 in such a way that EMM data is received: socat tcp-listen:40773,fork,reuseaddr system:'arib-b25-stream-test -v 1 -m 1 -p 1'.