custom ports in google load balancer for IPv6

I am running an MQTT (on custom port) server on the google compute engine. I need it to run on IPv6 network. After looking at the google docs (https://cloud.google.com/load-balancing/docs/ipv6) I figured out we need to use TCP load balancer to support IPv6.

Now the TCP load balancer does not support my custom port 19004

Is there a way out?