deploying WT web app on google cloud

I have build a wt (witty) hello world example and I am trying to deploy this on a Google Cloud instance. It seems to run fine locally (hence it has all the necessary library dependencies). However, I am not able to it to deploy on the server.

I am trying (using my actual http address which is different from the example below)

./hello --docroot . --http-address 105.150.47.754 --http-port 80

but it responds with

Error (asio): bind : cannot assign requested address

It seems to work fine using (0.0.0.0/0)

The cloud instance allows HTTP tcp/80 traffic.

I have tried

setcap 'cap_net_bind_service=+ep' ~/hello

to allow non-root users to publish on ports below 1024, but also to no avail.

Any suggestions?

Cheers, Mike