Getting disconnected from NT network

I have several workstations ( Windows 95 ) that occasionally “loose” connection to the NT network. I am using TCP/IP allowing each workstation to receive an IP address from the DHCP server. I have PDC and a BDC NT Servers, I have disabled each workstation’s ability to become Windows Browse Master and have set LM Announce to Yes.

But randomly the workstations will loose connection to the network. Can someone help ?