Which ports on clients should I open on my firewall for ZelloWork? TCP ports 80, 443 and 28225 need to be open for ZelloWork to send data and connect to our servers. For the best performance, open UDP ports 1025 through 65535. Note: These are outbound ports. Zellowork Support January 13, 2017 21:33 Follow Have more questions? Submit a request 0 Comments Please sign in to leave a comment.