--- title: Why are my receivers showing offline in CMSE after their IP address was updated?  description: Receivers Drop Offline After DHCP Lease Renewal --- [Skip to content](https://commercial.screenbeam.com/en/support/why-are-my-receivers-showing-offline-in-cmse-after-their-ip-address-was-updated#main-content) English Show submenu for translations [![ScreenBeam logo](https://commercial.screenbeam.com/hs-fs/hubfs/ScreenBeamLogo-Zendesk-2.png?width=180&height=22&name=ScreenBeamLogo-Zendesk-2.png)](https://www.screenbeam.com/) Open main navigation Close main navigation - English Show submenu for translations - [Open Ticket](https://helpdesk.screenbeam.com/ticket) [Open Ticket](https://helpdesk.screenbeam.com/ticket?hsLang=en) How can we help? - There are no suggestions because the search field is empty. 1. [Commercial Knowledge Base](https://commercial.screenbeam.com/en/support?hsLang=en) 2. 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[CMS Enterprise](https://commercial.screenbeam.com/en/support/known-issues-troubleshooting-tips?hsLang=en#cms-enterprise) # Why are my receivers showing offline in CMSE after their IP address was updated? ## Receivers set to DHCP can lose contact with ScreenBeam CMS Enterprise (CMSE) after their lease expires and they receive a new IP address. ### Errors - Receivers that were online in CMSE show as offline or disconnected. - The receivers still power on, display the Ready to Connect screen, and accept screen mirroring locally. - Configuration changes, policies, and firmware pushes from CMSE do not reach the affected receivers. - The problem appears after a DHCP lease renewal or a reboot, often days or weeks after a working install. - The IP address on the receiver's Ready to Connect screen differs from the one CMSE last recorded. - \\ ### Cause  The cause is a firewall blocking TCP 7237, the bidirectional channel receivers and the CMSE server use to communicate.  ### Fix 1. To fix it, allow TCP 7237 for the receivers' entire DHCP scope or VLAN, not for individual receiver IPs. 2. Confirm the receivers are set to DHCP and note the IP each one currently shows. 3. Check the firewall for rules covering TCP 7237 between the receivers and the CMSE server. 4. Replace any per-IP rules with rules covering the receivers' full DHCP scope or VLAN. 5. Allow TCP 7237 in both directions: receiver to server and server to receiver. 6. Verify the CMSE server has a static IP or a stable DNS name. 7. 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