What is wrong with linux forwarding ipv4?

Question

linux

What am I doing/not doing right?
there are two "boxes", on both linux,
on one hurdy-gurdy asus p5q se (one network port)
on the second Gigabite GA-EP45 DS3 (two ports)
in both /etc/sysctl.conf it is written
net.ipv4.ip_forward=1
asusovaya does not see the network from gigabytes
for
ports of course working

Answer 1

PS
it was also necessary in the network manager

share network