@No4 The only difference between the settings you have listed and mine are that I'm using 1500/1492 MTU size instead of 1508/1500. I'm only running IPV4 so, as per the comments from @fe31nz above, it isn't an issue, however his comments suggest either should work on the Edgerouter. I'm getting full speed (950Mbps/450Mbps) from my fibre so pretty happy.