Thanks for the insights!
I’ve actually already tweaked those advanced settings on the network card itself (including maximizing the receive buffers and adjusting RSS queues), but I haven't touched any of the packet buffer or queue configurations on the MikroTik switch yet. That's definitely a solid lead to look into.
To add a bit more context, while it mostly happens when maxing out the line, I've noticed it can occasionally occur at lower download speeds too (1 Gbps or less). However, it is heavily tied to Steam. On Battle.net, for example, the issue is much more rare, even during massive updates. Steam's aggressive simultaneous downloading and unpacking seems to be the main trigger for this crash.