Hi Sergio,
I have seen permissions errors but not timeouts. I would try to isolate the issue as follow:
1- Create a new VM using one of the public images provided by Google, make sure that you keep ¨Allow default access¨ so that the instance has reading permissions on Cloud Storage. Create a new bucket using the WUI. Log in the new VM and run ¨gsutil ls¨. That should list the buckets in your project. Try to display the files in the bucket using ¨gsutil ls gs://bucket-name
2- Are you running a firewall in your VMs that could be blocking connections?
3- Make sure that you have the latest component versions by running ¨gcloud components update¨.
4- If you allow ICMP traffic, are you able to ¨ping api.google.com¨?
5- Are you able to list the bucket (gsutil ls) but not the content (gsutil ls gs://bucket)?
6- Make sure that the tool is correctly authenticated running
a) gcloud auth list (This output should show the account used)
b) gcloud config list (This output should display your project)