It takes some time to compile and configure a good firmware.

Especially you need to check what setting do you want to config in the firmware, like those in /etc/config/ and save the contents to files and put them in openwrt path before you compile.

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But it is not easy to configure a good firmware. We have made some good progress to automatically connect WISP repeater so that you don’t need to reset your router if it cannot connect. Also, I don’t think TAP works good in router. Seems only TUN works. The reason is that TAP will try to bridge all the clients, which seems a problem for the router. It can bridge the router with other openvpn clients, but the router cannot give an IP address to each devices from your openvpn server.