The nuget package NetworkPrimitives.JsonConverters contains some basic System.Test.Json converters for the NetworkPrimitive types.
var jsonSerializerOptions = new JsonSerializerOptions();
// Option 1: Add both IPv4 and IPv6 converters
jsonSerializerOptions = jsonSerializerOptions.AddNetworkPrimitivesConverters();
// Option 2: Add only IPv4 converters
jsonSerializerOptions = jsonSerializerOptions.AddIpv4Converters();
// Option 3: Add only IPv6 converters
jsonSerializerOptions = jsonSerializerOptions.AddIpv6Converters();