Thanks Chris, I had to web search, odd.
Harold,
Let's also document this. We can talk offline after you have success.
Step 1, I believe I had to add the following to ampr-ripd.c - as I don't see it in Marius' version (there's ancient discussion on this). I added it after the last includes at the top:
# define IPPORT_ROUTESERVER 520
This is from the .bash_history of my VM when creating for the WAX202:
tar -xvf openwrt-sdk-22.03.0-ramips-mt7621_gcc-11.2.0_musl.Linux-x86_64.tar.xz
ls
unset SED
export STAGING_DIR=/home/user/openwrt-sdk-22.03.0-ramips-mt7621_gcc-11.2.0_musl.Linux-x86_64/staging_dir/toolchain-mipsel_24kc_gcc-11.2.0_musl/
export TOOLCHAIN_DIR=$STAGING_DIR
export LDCFLAGS=$TOOLCHAIN_DIR/lib
export LD_LIBRARY_PATH=$TOOLCHAIN_DIR/lib
export PATH=$TOOLCHAIN_DIR/bin:$PATH
cd /home/user/ampr-ripd-2.4.1
ls
mipsel-openwrt-linux-musl-g++ ampr-ripd.c -v -fpermissive -o ampr-ripd-2.4.1-mipsel
sha256sum ampr-ripd-2.4.1-mipsel
exit