When is ASP.NET Core's HttpContext.Connection.RemoteIpAddress null?

Question

One uses HttpContext.Connection.RemoteIpAddress to get a client's IP address.

Microsoft.AspNetCore.Http.ConnectionInfo.RemoteIpAddress is marked as nullable.

It will be null when behind a reverse proxy server. (In that case the UseForwardedHeaders middleware must be used.)

The docs linked above just say "Can be null" - under what other conditions can it be null?