it may be the shields firewall is stopping port 23.
I think this may have something to do with it. Usually, firewalls have a 'block all' setup to start. Then you begin to punch holes by creating rules to allow certain ports. I think, but haven't looked into it, that you may need to look closer at giving port 23 permission through the firewall. Maybe someone else who knows this better could chime in.
Shield Pro v1, Chaos Calmer, FW 1.51 SP1, v8.3.2, Bridge Mode