I really held back from asking this question, but I have spent almost all day on this.
I have a Google Compute Engine Instance with Plex installed, but I can't connect to it via SSH tunnel for the initial setup.
VPC firewall rules
All ports for ingress and egress with source IP 0.0.0.0/0
From mac terminal
ssh 35.198.xxx.xxx -L 8888:localhost:32400
After visiting http://localhost:8888/web
channel 4: open failed: connect failed: Connection refused