Jen, I use a standard cat5 flylead with a custom db9 adapter. If you have the Eq6 with db9 you can find the adapter info in
this post
@ Raymo, crimps can be dodgy, depending on how firmly the crimp is done, the gold fingers within the connector can end up pushed in too deeply and can have problems contacting the socket connectors.
I've fixed many problems by crimping the connector less tightly with just enough pressure to ensure the gold crimp fingers penetrate the cable but don't go right through. If your cat 5 cable is made of solid rather than stranded cable then it could also be that the connectors are going O/C.
Solid conductor cable doesn't take well to being fitted with RJ plugs even of the plugs are specifically designed for solid conductor cable. There are lots of other possibilities including dry solder joints within the handbox.