[erlang-questions] A (hopefully simple) diameter relay question

[QDev]

Hi folks,

Hopefully I'm being a bit dense and missing some obvious configuration here, but how do I get the OTP application to relay diameter messages to another (externally hosted) diameter server? I start my service with {'Auth-Application-Id', [?DIAMETER_APP_ID_RELAY]}, {restrict_connections, false} and {use_shared_peers, true}, and then start a listener and a relay to the upstream using the example peer module:

peer:connect(?MODULE, {tcp, loopback, 13868}),
peer:listen(?MODULE, tcp),

However whilst my callback module's handle_request gets called fine, when it returns {relay, [{extra, [relayed]}]}, in the corresponding pick_peer/5 callback there are no remote (or local) peers to select from! Do I need to add additional service configuration in order to relay to another diameter server? The server I am trying to "forward" traffic to is *not* an Erlang/OTP server btw, but some other diameter server (or as it happens in this particular case, a diameter test bed server running on seagull).

Cheers,
Tim