CCR2004-1G-12S+2XS SFP28 ports stay at no-link with 5 m Solid Optics 25G DACs to an FS S5860-20SQ

Two Solid Optics SFP-H25GB-CU5M SFP28 DACs between a MikroTik CCR2004-1G-12S+2XS and an FS S5860-20SQ switch produced status: no-link on sfp28-1 and sfp28-2 with auto-negotiation off, 25 Gbps, full duplex, FEC91 and no flow control; RouterOS 7.8rc1 was tried on vendor advice. The modules were recognised (Solid Optics vendor, EEPROM checksum good, no rx-loss or tx-fault), and the ports only linked wheen forced to 10 Gbps. No replies were poosted.

• Hardware: MikroTik CCR2004-1G-12S+2XS, FS S5860-20SQ
• Transceivers: Solid Optics SFP-H25GB-CU5M SFP28 DAC 5 m
• Form factor: SFP28, DAC

Symptoms / messages:

status: no-link at 25G
link only at 10G
EEPROM checksum good