Multicast only crc errors

[jenix]

Hey everyone

I am experiencing the strange issue, that IPTV multicast packages sent from OPNsense to my switch are dropped there due to crc errors. My OPNsense (a DEC840) is connected to an Aruba 2540 via DAC. Everything worked fine until I had to replace the disk of the DEC840 recently. I did a clean reinstall of 24.1 and imported my previous config. Everything is working fine apart from my IPTV setup. All the configuration is correct (and was working previously) on the OPNsense side, I can see the IGMP subscription and the broadcast of the multicast stream into the network.
However, the Aruba switch is claiming that it receives the multicast packages with crc errors (or "FCS errors" as Aruba / HPE calls it). The strange thing is, that this only applies to the IPTV multicast packages. As soon as I subscribe to a stream on a client, the RX errors on the switch port connected to the OPNsense firewall go through the roof until I stop the stream / unsubscribe again. Then all RX errors stop as well. I do not see any errors with other traffic, independently of the amount. This lets me believe that this is not a physical issue as I would expect that crc errors would appear with 'normal' traffic as well.

As the whole setup / configuration of the switch has not changed, the only possibility that I see is that OPNsense somehow messes up the crc computation of the packages. I tried to enable the CRC hardware offloading, but the issue is still the same. Now I'm at a loss how I can debug this issue further or what I can try next.
Does anyone has an idea? Any help is really apprechiated.

Thanks already.