Это, как раз, по сложному.
Если по-простому, покажите вывод команд
все команды с сервера или с клиента тоже показать?
[root@altlinux-school-server7 ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp5s9: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:21:91:db:2e:58 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.1/24 brd 192.168.0.255 scope global enp5s9
valid_lft forever preferred_lft forever
inet6 fe80::221:91ff:fedb:2e58/64 scope link
valid_lft forever preferred_lft forever
3: enp5s2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:0b:cd:b4:14:79 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.77/24 brd 192.168.1.255 scope global enp5s2
valid_lft forever preferred_lft forever
inet6 fe80::20b:cdff:feb4:1479/64 scope link
valid_lft forever preferred_lft forever
[root@altlinux-school-server7 ~]# ip r
default via 192.168.1.1 dev enp5s2
192.168.0.0/24 dev enp5s9 proto kernel scope link src 192.168.0.1
192.168.1.0/24 dev enp5s2 proto kernel scope link src 192.168.1.77
[root@altlinux-school-server7 ~]# iptables -nL -t nat
Chain PREROUTING (policy ACCEPT)
target prot opt source destination
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Chain POSTROUTING (policy ACCEPT)
target prot opt source destination
[root@altlinux-school-server7 ~]# cat /proc/sys/net/ipv4/ip_forward
1