All was well, and performance seemed good. Until I decided to pull a large file from the server to my laptop. Despite being almost next to the 802.11ac access point, I was struggling to get even 5MB/sec. It appeared that the noise level on the WiFi channel was quite a bit higher than it should have been. Looking around with a SDR found what looked to be a wireless AV sender blanketing a wide chunk of spectrum in noise. Moving channel only increased performance to about 10Mbit/sec so I plugged into wired ethernet and tested with iperf.

Accepted connection from 172.16.1.19, port 55062
[  5] local 172.16.1.20 port 5201 connected to 172.16.1.19 port 55063
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  5]   0.00-1.00   sec  17.1 MBytes   143 Mbits/sec  282   12.7 KBytes
[  5]   1.00-2.00   sec  17.3 MBytes   145 Mbits/sec  266   22.6 KBytes
[  5]   2.00-3.00   sec  17.5 MBytes   147 Mbits/sec  264   14.1 KBytes
[  5]   3.00-4.00   sec  17.2 MBytes   144 Mbits/sec  282   14.1 KBytes
[  5]   4.00-5.00   sec  17.3 MBytes   145 Mbits/sec  251   12.7 KBytes
[  5]   5.00-6.00   sec  17.4 MBytes   146 Mbits/sec  250   12.7 KBytes
[  5]   6.00-7.00   sec  17.8 MBytes   149 Mbits/sec  282   15.6 KBytes
[  5]   7.00-8.00   sec  17.2 MBytes   144 Mbits/sec  295   12.7 KBytes
[  5]   8.00-9.00   sec  17.3 MBytes   145 Mbits/sec  268   12.7 KBytes
[  5]   9.00-10.00  sec  17.8 MBytes   149 Mbits/sec  292   22.6 KBytes
[  5]  10.00-10.01  sec   255 KBytes   247 Mbits/sec    4   14.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  5]   0.00-10.01  sec   174 MBytes   146 Mbits/sec  2736             sender
[  5]   0.00-10.01  sec  0.00 Bytes  0.00 bits/sec                  receiver

Yeah, that’s not good. Further testing revealed it only affected traffic being switched from a 10Gbit to 1Gbit port.

Tried putting the “stable” and “latest beta” RouterOS on the CRS317, no change. Tried SwOS too in latest and older varieties - although I couldn’t get 2.3 to boot at all (known bug that crashes it on boot if you have any SFPs plugged in (!) but it seems worse than that for me).

I opened a thread on the Mikrotik forums, apparently it’s a “known problem”. I see that the patch notes mention a similar issue on the CRS326…

I’ve changed the network layout to route between two separate subnets, one for 10Gbit and one for 1Gbit. Performance is actually better - in the same configuration, about 950mbit throughput.

Hoping this is fixed soon, because until then I can’t really recommend the CRS317 on a “mixed” network.