How to save the Asus RT-AC66u router settings that were made via telnet?

Question

ASUS

When raising the VPN, the router prescribes the default route through the VPN server, this can be easily fixed by deleting the default route and setting the route to the subnet through the interface. The IP utility works on the Linux router. But the settings live until the reboot. The /etc directory is linked to the /tmp/root directory, so scripts are hard to fix.
Is there any other utility in asus where you can control interfaces and routes, and where is there a command like "copy run-config startup-config"?