Connection times out

Hi all.  Still pretty new at this and at system administration.  I have 
2 Opengear CM4148 boxes which appear to be happily configured.  One has 
relatively few connections to support (about 8) and the other supports 
about 40.  Initially connection times and response times seemed to be 
quite good.  Lately though, the connections to the Opengear box with 8 
ports occupied is a little slow.  Connections to the Opengear box with 
40 ports occupied frequently times out before even presenting a login 
prompt.  This is true of both ssh and https connections.  I tried to 
ping the Opengear box and notice that I have 30 - 40% packet loss over 
30 - 35 pings.  I've change the port on our network switch and tried a 
new network cable.

Has anyone else had this experience?

Thanks in advance,
Lisa Doherty