To any other sad soul that still had problems after following this otherwise great tutorial - in my company we use Cisco AnyConnect VPN. This borked the network connection of WSL, so I followed this: gist.github.com/machuu/7663aa653828d81efbc2aaad6e…
...but this step possibly (don't ask me to double-check ;)) messed up the DISPLAY var step, so here's mine:

export DISPLAY=$(route.exe print | grep -w 0.0.0.0 | tail -1 | awk '{print $4}'):0.0

^ basically you want this to be host ip assigned by the VPN, so double check if those are the same and if not tweak i.e. tail param