I see the issue, I have a 10GBASE-SR  850nm MMF. My friend who works in networking got it for me. I don't think it's an Arista thing, it works with the 1310nm one, it's fixed.

Good that it works now.

Its clear that 850nm wouldn't work combined with RME (1310nm).

Regarding SFP firmware, its difficult to predict which firmware works or is too special.

SFPs for Brocade won't work with Cisco.
In my PC with Intel X710-DA2 card I need SFP+ with Intel firmware otherwise the transceivers won't work.

What's the URL of the Arista SFP module? Problem can be that it has special firmware for Arista, then it won't work.

You need multimode SFP with 1310nm (not 850nm) and without any special firmware. Therefore I always recommend to use those from RME to not get into such issues.

See this post from this evening, I picket one from fs.com that might work before you start fiddling around with BNC cabling.
https://forum.rme-audio.de/viewtopic.ph … 14#p230014
Stick to optical, it gives you also galvanic isolation.

Use MADI frame size of 96k on both devices, then you can also switch between single and double speed.

I recently purchased an unlock code fro the ferrofish Pulse. I am using an Arista MMF SFP which is recognized by the pulse and its transmitting light. I looked in the back of my RME Fireface UFX3 and did not see a laser being transmitted from the output port. Is there something else I need to do in order to get this to work?

Computer
Mac Studio M2 Max
USB3
Fireware: v20
Driver: v4.17
AES to ADI-2 Pro

Settings:
Madi Output - optical
Madi Format - 64
Madi Frame - 48K

Edit: So when I slave the RME UFX3 to the Ferrofish pulse via MADI,  I see the green MADI light. I obviously want the RME UFX3 to be the master but again still no laser output from the RME UFX3.