Just flashed my Archer C7 with the latest firmware 18.06. I`m not sure if I installed the factory.bin or upgrade.bin because only one of them worked to flash the router.
I ran opkg update and it everything worked great. Then I tried to run opkg install openvpn-openssl and got an error message cant install package openvpn`. The firmware is not a custom build, but the file that was downloaded for the Archer C7, V4.
@DjiPi, I managed to get OpenVPN-openssl and easy-rsa installed. The problem was that I had my laptop connected to the C7, then a LAN cable to another router, then to a CM from my ISP and out to the internet. My browser connected fine to the internet but the opkg update showed some network errors.
Now if only I could get the OpenVPN to connect to ExpressVPN. I will read the forums for help on that one.