BiDi SFPs on a CRS326-24G-2S+ (SwOS): light received at -6 dBm but no link until auto-negotiation is disabled

Two FS.com 1G BiDi SFPs (1490/1310 and 1310/1490 nm) in a MikroTik CRS326-24G-2S+ running SwOS 2.9 detected incoming light around -6 dBm but never established a link; the same optics linked on a Netgear switch. The poster asked whether a manual speed setting was needed and whether RouterOS would behave differently.

• Hardware: MikroTik CRS326-24G-2S+, Netgear switch
• Transceivers: FS.com 1G BiDi SFP 1310/1490, FS.com 1G BiDi SFP 1490/1310, MikroTik 1.25G BiDi 1310/1550
• Form factor: SFP

Symptoms / messages:

RX power -6 dBm but no link