Hello

We have a router Mercusys & just added TP Deco x55

one by router in middle bedroom

one in lounge to Ethernet into sky later

one in daughters bedroom in attic & my office is along the hallway

has helped my daughters connection in bedroom 

my office seems to be working ok despite speed test showing low on laptop in there but showing higher on iPhone & iPad not sure why 

however on my laptop it says no internet, secured but continues to work ok why is this?