My new employer has two subnets, x.y.74.\* (with default gateway x.y.74.33) and x.y.75.\* (with default gateway x.y.75.1).

The .75.\* subnet is reserved for servers, i.e. machines that offer services to the outside Internet. The .74.\* subnet is for machines that only need read-access to the Internet.

From x.y.74.62, I need to access x.y.75.3 in order to make automated backups. Unfortunately, if I try to ssh to .75.3, I get a "No route to host" error. Mysteriously, establishing a ssh connection to .75.4 works perfectly.

Both .75.3 and .75.4 have the same routing table and the same ARP table. Neither one is using a firewall.

How can it be that I can reach one server, but not the other?

And more importantly, what else can I try to make .75.3 reachable?