Hi
What do you mean by nat routing in your title?
Based on your description you want to for to specific interfaces based on tcp ports for inbound traffic on your cellular interfaces. This can be achieved using PBR (policy based routing).
The goal with PBR is to define an acl, and based on that all (using a route-map) you'll tell the router to go to a specific outside interface or a specific next hop ip.
I won't type all commands because there is a great post done to explain each steps:
https://community.cisco.com/t5/networking-documents/how-to-configure-pbr/ta-p/3122774
Thanks
Francesco
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