[Skunkworks] cant ping machines in workgroup

I have a workgroup with 3 machines. I have a switch and a zuku router TP LINK. The machines in the workgroup can connect to the internet and can ping the router but they cannot ping each other. before the router was connected i could ping my clients machines... My query is ......Does a tp link need some enabling for the work group to be able to ping each other. Is there something i need enabled on the router?