Clear KnownNetworks and KnownProxies if none are configured explicitly

Jellyfin.Server/Extensions/ApiServiceCollectionExtensions.cs

@@ -152,6 +152,13 @@ namespace Jellyfin.Server.Extensions
                 .Configure<ForwardedHeadersOptions>(options =>
                 {
                     options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
+                    if (knownProxies.Count == 0)
+                    {
+                        options.KnownNetworks.Clear();
+                        options.KnownProxies.Clear();
+                    }
+                    else
+                    {
                         for (var i = 0; i < knownProxies.Count; i++)
                         {
                             if (IPAddress.TryParse(knownProxies[i], out var address))
@@ -159,6 +166,7 @@ namespace Jellyfin.Server.Extensions
                                 options.KnownProxies.Add(address);
                             }
                         }
+                    }
                 })
                 .AddMvc(opts =>
                 {