LibreCMC patched a bug in the IPv6 kernel code, after I filed a bug report. The official build might not come out for a while, but here is my build for the GL-AR300M (NAND):
ftp://lavender.qlfiles.net/librecmc/v1.4.4-a7ce8a7e36/librecmc-ar71xx-nand-gl-ar300m-ubi-factory.img
The Libre Hacker 