Ensure that you enable Auto-Negotiation for ports with 100GbCR4 modules plugged in.
Although Auto-Negotiation is mandatory as per the 100GbCR4 standard, and this is the default software configuration, you can disable Auto-Negotiation to connect with older systems that do not support it. The system does not support FEC on 100GbCR4 links with Auto-Negotiation disabled.
For more information about FEC, see Forward Error Correction.