Linux as router with iptables

sudo sysctl -w net.ipv4.ip_forward=1

sudo iptables -t nat -A POSTROUTING --out-interface wlan1 -j MASQUERADE

sudo iptables -A FORWARD -i wlan1 -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o wlan0 -j ACCEPT

In this case, wlan1 is where all the traffic will be routed to.

Solve problem of unreachable networks

Probably it needs to set metrich in “/etc/dhcpcd.conf”

interface wlan0
metric 100