I've got a Deco X50 system with 2 satellite units connected wirelessly.  All on the latest firmware, and with a recent channel optimization run.

If I use a wired connection to the main deco or any of the satellites then I get the full speed of my connection i.e. 380 download / 35 upload.  A wireless connection to the main deco also gives the same result.

However - if I connect via wireless to the satellites i only get a maximum of  275 download / 35 upload, even if I am stood right next to the satellites.  I've tried this with several different wireless devices with the same results.  Any idea what could be causing this?  According to the app there is a Strong signal to both satellite units.