As part of our ongoing infrastructure modernisation, we are making changes to the third‑party services used by Symphony Cloud. These changes require customers with firewall restrictions to update their configuration to ensure uninterrupted service. The following changes require your attention:
Update your Firewall Configuration - Symphony Cloud
1. New Service: NTP (additive change — no removals)
To ensure uninterrupted service, customers with IP- or DNS-based firewall restrictions must update their firewall configuration until 15 December 2026 and allow the following destination:
| Service | Protocol | Port number (Symphony Cloud) | Host (local) | Host (Symphony Cloud) |
| NTP | UDP | 123 | Devices | time.cloudflare.com |
Important: The existing NTP server continues to run in parallel. Please keep pool.ntp.org allowed, as it remains in active use. No rules need to be removed. This is an additive change only.
2. STUN service consolidation (removal of obsolete STUN rules)
We have streamlined our STUN configuration and now use a single STUN server for the Mobile Clients and Web Clients.
Effective from 11 November 2026, Symphony Cloud uses only stun.l.google.com for STUN. Please ensure that this destination is allowed in your firewall configuration.
| Service | Protocol | Port number (Symphony Cloud) | Host (local) | Host (Symphony Cloud) |
| STUN | UDP | 3478 | Mobile devices, computers with Web Client, web portal | stun.l.google.com |
Important: From this date onward, you can remove all other STUN servers from your firewall rules (if previously configured).
If you have any questions or need help updating your firewall configuration, please see the Symphony Cloud firewall documentation on cLibrary or reach out to our support team.