golang won't accept connection

hello

my problem is i can’t connect to Golang deployed on windows vps

the topology

My Phone sends client registration data to -> Cpanel (lumen) -> PHP API deployed on windows server. work

and then i migrate to golang

My Phone sends client registration data to -> Cpanel (lumen) -> Golang API  deployed on windows server with port 80. work

the problem is here

My Phone sends client registration data to -> Cpanel (lumen) -> Golang API with custom port (8899) it doesn’t work

i have added rules for 8899 in firewall but still won’t work.

i tried to turn off firewall too but still won’t work

anyone can help?

thanks

Have u setup golang web server to listen port 8899?
Can you provide golang code?