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Known update issues

FortiOS 7.6.8: 100G FR transceiver link fails with RS-FEC enabled on 7121F-2

WorkaroundKnown issue

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Summary

The FortiOS 7.6.8 release notes list a known issue (Bug ID 1336373) on the FortiGate 7121F-2 (FIM-7941). A 100G FR transceiver on port 1-P4 does not establish a link when RS-FEC (Reed-Solomon forward error correction) is enabled. The link works with FEC disabled. Fortinet has confirmed the issue; no fix is stated yet.

Symptoms

The link on port 1-P4 with a 100G FR transceiver stays down while RS-FEC is enabled. With FEC disabled, the link comes up.

Affected

  • FortiOS 7.6.8
  • FortiGate 7121F-2 (FIM-7941), build b0245, port 1-P4
  • 100G FR transceivers with RS-FEC enabled

Workaround

  1. Disable FEC on port 1-P4. According to the release notes, the link works with FEC disabled. The remote end must use the same FEC setting.

Fix

Not fixed yet.

Recommendation

If you use 100G FR transceivers on a FortiGate 7121F-2, check the FEC setting on port 1-P4 before or after upgrading to 7.6.8. Use FEC disabled on both link ends as a workaround and plan the upgrade in a maintenance window. Watch the Fortinet release notes for a fix.

Sources

Compiled from the sources listed and translated with AI (Claude); status and dates come from the vendor. The vendor’s statements are authoritative. Updated 1 Nov 2026, 22:02.

Where the information comes from

We continuously read the vendors’ official sources, community reports and trade media and summarise them in our own words, with a link to the source:

  • Microsoft: Windows release health (Windows 10/11, Server 2016 to 2025), Windows message center, known issues of Microsoft 365 Apps (Outlook, Excel, Word, PowerPoint), Edge, Intune, Autopilot, Windows 365 and Entra Connect, Microsoft KB articles with timelines, Exchange and Windows IT Pro blogs, optionally Microsoft 365 service health and message center
  • other vendors: Veeam KB, Citrix (known issues), Ubuntu and Debian (regressions), Broadcom (VMware), Fortinet, Cisco, Mozilla, Let’s Encrypt
  • community (title, short excerpt and link only, without the names of the authors): Microsoft Q&A, Microsoft Tech Community (discussions), Veeam R&D Forums, Eleven Forum
  • targeted web research with AI (Claude), e.g. on the updates of the month – this also finds discussions on Reddit and in forums; such entries are labelled as community reports until the vendor confirms them
  • early warning from trade media (title and link only): Born’s Tech and Windows World, BleepingComputer, AskWoody, Windows Latest, Windows Central, gHacks, The Windows Club, Deskmodder, Dr. Windows, WindowsArea, Frankys Web, heise online

Summary and translation with AI (Claude by Anthropic) – without any data of visitors.

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