It’s not the answer you’re looking for but if this still holds as possible since January in the long term it would be a much better VPN experience:
The Slate AX (GL-AXT1800) is near identical in specs to the Flint (GL-AX1800) inc. stable firmware.
… once online you can set any Encrypted DNS provider you’d like (eg: Cloudflare via DOH) to use in the VPN tunnel instead of your VPN provider dictating the DNS.