Problem solved, in the switch under port -> security, the value for 'Max Learned MAC' for the port connecting the router and switch was set to 10, way to low for all the traffic between the nodes at each end of this connection.
I have a problem with my openwrt router setup.
I have a switch connected to one of the router ports. When connected to the router ( either cable or wireless) I cannot ping any device behind the switch.
When connecting to the PC to the switch I can see all devices both connected to router and switch.
So it seems that lan traffic in the switch between LAN ports is restricted only to devices directly connected to the router. Is this an issue with the settings of the firewall in the router? Router is a wrt3200mcs from linksys, switch is a 24 port tp-link switch,sl3428