Dont use any of those converters they are all terrible. Use Handbrake to do conversion, start with the normal preset and see if that works, if it doesnt then try the universal preset.
The DMP-BT220 is a fairly lame media player, Panasonic don't explicitly state that it supports MP4 over DLNA in fact the manual states MP4 only works over SD card & USB. What it does mention though is MKV, try using MKV as the container in Handbrake and see if that works too.
You can repackage existing H.264 MP4 videos into MKV using MKVmerge.