I got a Mikrotik CRS510-8XS-2XQ-IN (RouterOS 7.11.2) with two Mellanox ConnectX-4 MCX455A-ECAT (updated firmware and configured for ethernet) and four Intel SPTSBP2CLCKS INTEL 100G-CWDM4 transceivers.
I’ve tested the Mellanox cards with the transceivers and could link up my Mac Studio (via Thunderbolt enclosure) to a test server (FreeBSD) and they negotiated 100G.
But I ran into issues connecting the server with the CRS510 using the same transceivers/cable as the link negotiation fails.
If I connect both QSFP28 ports on the CRS510 with those transceivers to each other, I get a 25G link on the first of the 4 sub-ports on each.
I guess the switch does not properly recognize the module and does not combine the 4 25G ports to one 100G port.