ConnectAsync is failing "Cannot resolve DNS for localhost"

Summary: When trying to use ConnectAsync, error "Cannot resolve DNS for localhost" This was reported on the forums - https://forums.couchbase.com/t/net-couchbase-client-3-0-issues/25591

Repro:

1. Install Couchbase Server locally (I'm using Community Edition on Docker). Credentials Administrator/password.
2. Write a .NET app and use the "connect to cluster" instructions in the documentation https://docs.couchbase.com/dotnet-sdk/3.0/hello-world/start-using-sdk.html (I have attached a project that reproduces).
3. Execute

Expected:

Connection to succeed and cluster object available for further use.

Actual:

Unhandled exception. Couchbase.Core.Exceptions.InvalidArgumentException: Cannot resolve DNS for localhost.
at Couchbase.Utils.IpEndPointService.GetIpEndPointAsync(String hostNameOrIpAddress, Int32 port, CancellationToken cancellationToken)
at Couchbase.Core.DI.ClusterNodeFactory.CreateAndConnectAsync(HostEndpoint endPoint, CancellationToken cancellationToken)
at Couchbase.Core.ClusterContext.BootstrapGlobalAsync()
at Couchbase.Cluster.Couchbase.Core.Bootstrapping.IBootstrappable.BootStrapAsync()
at Couchbase.Cluster.ConnectAsync(ClusterOptions options)
at ForumQuestions.Program.Main(String[] args) in C:\zproj\ForumQuestions\ForumQuestions\Program.cs:line 18
at ForumQuestions.Program.<Main>(String[] args)
----------------------Context Info--------------------------
null

Notes:

There is another issue reported in the same forum post. It might be related, but I don't know since I can't get past ConnectAsync.