Transaction Replication: Trying to add a Subscriber in a different domain

I am on the publishing server trying to add a new subscriber that is on a different domain. We have a trust between the domains and I can connect to the subscriber using sms on the publishing server using the servername\instancename.

When trying to setup the subscriber using SMS and "servername\instancename" I get "The server was not found or accessible". If I include the domain suffix "servername.123.com\instancename" it immediately comes back telling me "SQL Server replication requires the actual server name to make a connection to the server" and tells me the actual server name to use.

So with the full servername with the domain suffix it connects but says I need to use the actual name. With the actual name it pauses and comes back server not found.

I have tested the ability to ping from publisher, distributor and subscriber and I can ping all servers without having to use the domain suffix.

Server versions: Publisher 2005, distributor 2008R2, subscriber 2014. I do have this scenario working with all 3 on the same domain. My problem is now the subscriber is on a different domain.