Either add plex.direct to your router’s DNS rebind protection exemption list, or go to PM4Ks AddonSettings (outside of PM4K, long press the icon, Settings, System, uncheck both “plex.direct: Honor …” settings, then start PM4K again; then it should prompt you that it has found plex.direct domains that it wants to add to your advancedsettings.xml confirm that, restart CE, happy camper).
You have a non-trivial network/Plex setup.
