[sudo-sys] can't reach door computer

Did something happen to the omni door computer? I can't reach it over the network, even from within the building. It appears to be working, letting people in. I tried looking at the box, but couldn't make sense of the mess of cables. Maybe an ethernet got disconnected somewhere? The rest of the network is fine. Other devices on that subnet and that interface are reachable, but: $ ip neigh | grep 100.64.64.11 100.64.64.11 dev enp3s2 FAILED