Hi Moustafa
By default DLP listens on port 10025 (Server Socket Port)and send to the next hop on port 10026(MTA Resubmit port) , please adjust these ports accordingly when send the traffic from the exchange to DLP and DLP to the next hop
You can change these ports on the network prevent for email from server settings. and restart the services after that.
Please make sure that the DLP can handle the email traffic to not cause any delays to the email flow.
Thanks!