Network problem, what's wrong?

Question

linux

There is a computer with zoneminder with several cameras. Today one camera is disconnected - does not respond (but the others work).
However, there is a ping from other network nodes both to the server and to the camera. There is a ping from the camera to the server. Ping, in fact, disappeared unilaterally from one network node and only to one camera (and not to all). Rebooting the camera and computer did nothing. Replaced the switch not managed - as well.
I can not understand what the problem could be and in which direction to dig.
Local network, wired.
Computer: Ubuntu 16.04
ifconfig eno1

inet addr:192.168.18.9  Bcast:192.168.31.255  Mask:255.255.224.0

Camera:
ip: 192.168.18.122 netmask: 255.255.224.0

Answer 1

Is everything connected to one switch?
Have any new devices been added to the network lately?
What does arp -a show from the server after trying to ping the camera?

Answer 2

routing table "to the studio".