Re: It's (almost) never the instrument.
"It's network. It must be network." said everyone that isn't a network guy.
Get that all the sodding time, As a network engineer i can tell you from personal experience that 9.9999 times out of 10 its not a network problem and some issue on the source or destination system.
Failures typically result in 100% loss, not intermittent connections or allow you to connect to systems in other subnets but not ones in the same especially when no fancy security stopping intra vlan comms is deployed. Is that route still on that second server interface?