What is the name of the domain?
What is the issue you’re encountering
Couldn’t connect to my service using cloudflare tunnels with abc.example.com:port format - as tunnel maps abc.example.com to host:port. What should I do to achieve this?
May I ask if you are, or rather you could use sub-domain mapping to e.g. localhost:different_port for each service. This would eliminate the need for port specification in the URL 
Are you mapping this or using reverse proxy on the origin host/server, such as Nginx?
Despite using tunnel, may I ask if you’re still using the supported and compatible ports as follows on the article below, or different ones for your service(s)?
Related to “client apps”, may I ask you to provide a bit more information what exactly or what kind of type of client apps?