Compile Linux Headers for Wireguard

Hello,

I’m trying to make Wireguard to work on Banana PI R2.

I’ve compiled the Linux kernel with the appropriate kernel modules (https://www.wireguard.com/install/#kernel-requirements) using @frank-w build tool.

However, when installing the wireguard I get the following message: Building for 4.14.69-bpi-r2-main, 4.15.0-34-generic and 4.4.70-BPI-R2-Kernel Module build for kernel 4.14.69-bpi-r2-main was skipped since the kernel headers for this kernel does not seem to be installed.

And my question is how can I get the headers on the kernel? I’ve tried a few variants while compiling, but none seems to work.