I came across these errors when I was creating Service Template for HA NVGRE Gateway:
The virtual machine or tier load balancer configuration requires an ip pool and there are no appropriate IP pools accessible from the host.
No available connection to selected vm network can be found.
After some troubleshooting I noticed that some of my port profiles do not match.
Make sure you have two Logical Switches deployed on your Gateway Hots. Here is my configuration:
LS-Management with Logical Networks and Virtual Adapters configured for Management, Cluster, Live Migration networks.
LS-Gateway (Front-End Network is enabled but no Virtual Adapters are created on GW Hosts)
In case you are using custom Port profiles and Port Classification, make sure they are properly configured.
Once I reviewed Switch settings on GW hosts and my Host ratings went back to normal.