Fixing no carrier with Flypro 10GBASE-T SFP+ on a Dell-branded X520-DA2 under Debian and FreeBSD/OPNsense

A Dell-branded Intel X520-DA2 with Flypro 10GBASE-T SFP+ modules showed no carrier (or no interface at all) on Debian and on FreeBSD-based OPNsense because the card rejects unapproved modules. The post collects the per-OS fixes and the permanent EEPROM approach. Hardware involved: Dell-branded Intel X520-DA2, Flypro 10GBASE-T SFP+.

• Hardware: Dell-branded Intel X520-DA2
• Transceivers: Flypro 10GBASE-T SFP+
• Form factor: SFP+

Symptoms / messages:

no carrier
interface absent