i use this port for messaging app and since i upgraded to Cloudflare i no longer have a functioning messenger
you are correct. You cannot use port 2700 on any hostname that is configured to use the Cloudflare Proxy. The Cloudflare Proxy only passes HTTP and HTTPS traffic, and only on specific ports. You can learn more here.
If you need to use other ports or protocols, you will need to configure a hostname that you can set to DNS Only.