Are you using Ubuntu by chance? Here’s how I route 3 different networks through one server using netplan. /etc/netplan/
This file describes the network interfaces available on your system
For more information, see netplan(5).
network:
version: 2
renderer: networkd
ethernets:
eth0:
dhcp4: no
addresses:
- 10.11.12.244/24
nameservers:
addresses: [10.11.12.10,10.11.12.11]
routes:
- to: 10.11.12.0/24
via: 10.11.12.1
- to: 172.16.1.0/24
via: 172.16.1.1
- to: 10.13.1.0/24
via: 10.13.1.1
eth1:
dhcp4: no
addresses: [52.38.22.49/28]
gateway4: 52.38.22.41
nameservers:
addresses: [8.8.8.8,75.75.75.75]