Mysterious connections in my network profile help needed!PLZ PLZ

aoa guyz

i got a ptcl 4mbps broadband connection a month earlier.the ADSL router model Echolife HG510a kept workin fine.i then added a hub or other router you may say to get additional access points through lan.and it was also ok.i then replaced the plian old router or hub with Tp-link wifi router and followed all the instuctions as recomended.untill that it worked 4 a while.but one day i checked my network group and foubd several other computers were shown in there.i thought it might be wifi connections.changed the security key bt at that point my TP-link wifi router was not able to i removed it.but even when i am using ptcl ADSL router and the same old my network Hub or router i keep on seeing these connections and sometimes there are almost 40-50 connections can it be possible becuse only have 10 lan ports (4 on ptcl ADSL and 6 on other router).plz somebody explian and tell what is the isssue and what can i do.plz plz plz