AFP protocol very slow..? Balance 30

I have some port forwarding setup between Macs at different WAN locations. This is for file sharing that uses the Apple AFP protocol. But the transfer rate is very slow. On my Peplink in the port forward I use a TCP protocol - is that right? There is no AFP choice.

As a test when I use ChronoAgent between the same Macs on different WANS the transfer rate is very fast as ChronoAgent uses it’s own client app.

Why is the AFP speed so slow?
I suppose it could be my upload LAN to WAN which is not Peplink but it is slow from multiple locations.

I think it is the AFP protocol.??

AFP Protocol use TCP 548 port. I tried AFP over the Peplink through port forwarding and it is very fast. What is the throughput different between using AFP and ChronoAgent?

I think my problem is specific to that machine as other machines are working OK using the AFP. Thanks - I will continue to investigate