CRS309-1G-8S+IN limited to 2.5 Gbps internet speed?

RouterOS General
1

Hi All,

I’ve gotten pretty far on my own trying to figure this out but I seem to be at an impasse. I have also looked through the forum and found some cases that were somewhat similar but not quite the same (as most of those were dealing with 1G internet speeds and had different setups and situations).

Here’s my current setup/situation:

I have a Mikrotik CRS309-1G-8S+IN switch. I currently have a 100’ long, 5 Gbps Cat8 ethernet cable (also tried Cat6 and Cat7) from a Google Fiber router (which is confirmed outputting 5 Gbps) to SFP port 1 on the switch via an Ipolex ASF-10G-T 10GBase-T RJ-45 30-m ethernet to SFP+ transceiver.

Then I have my computer plugged into SFP port 3 on the switch via an SFP+ fiber optic 10GBase cable. That SFP+ fiber optic cable goes from the switch into a QNAP QNA-T310G1S Thunderbolt 3 to 10GbE Adaptor, which then plugs into my computer via the thunderbolt USB-C port (eJS45 [ethernet] port is limited to 2.5 Gbps).

At first, on my computer, I was getting about 4,850 mbps (wow) download but I was only getting around 500 mbps on the upload (all tests performed with speedtest.net, which is what google fiber recomended). Via WinBox>Quick Set, I updated the router OS on the CRS309-1G-8S+IN to the latest “Stable” version (7.11.2) and that got me up to 2.5 Gbps on the upload but the download has now also dropped to 2.5 Gbps. It should be showing around 4,850 mbps download AND 4,850 mbps on the upload - which is what I get when I connect directly to the router and don’t go through the CRS309. I then tried updating to the latest “Testing” version (7.12rc4) of the OS but that didn’t seem to affect internet speed.

I have tried plugging the computer and incoming internet signal via ethernet cable into different ports on the switch but that didn’t seem to change anything. Granted: I didn’t try every single port.

Any ideas what could be causing the 2.5Gbps cap? I know that it can download at 5Gbps because it was doing that speed before I updated the switch software/firmware. That indicates (to me) that it is not a hardware issue but instead, is something to do with the OS/firmware or settings.

PS. I am not an IT person or programmer or anything like that. I’m not very familiar with terminology for this stuff but I am slowly learning as I troubleshoot this. Just trying to allow the full internet speed through this router.

Any ideas on what could be happening?

2

100-feet long stretch of UTP cable is pretty long (it’s actually more than 30m which is rating of your SFP module). Even though it’s a CAT-8 and thus good for some high throughputs, reachable range depends on transciever’s power capabilities … and longer stretches require quite high power, not many SFP+ modules are capable of it. If power budget doesn’t suffice, then rate will degrade (lower speeds require less power). In addition, RJ45 SFP modules tend to run pretty hot and since your switch is passively cooled it might be that that module is actually overheating (perhaps it’s got an over-temperature protection which reduces Tx power to reduce temperature).

Speed autonegotiation is done by SFP modules, there’s very little ROS can do about it (apart from properly supporting the module which it seems to do).

3

You were right. The 100’ long CAT8 ethernet cable worked at full speed just fine when plugged into the PC PCI non-SFP ethernet port but when plugged into an SFP+ port on the switch via adapter, it was very slow. I purchased a second switch with SFP connection to put next to the router and then purchased and connected a 25 meter (~82’) 10G SFP+ “AOC” (pacifically AOC) cable and now everything is running at full speed. It was just the CAT8 cable (connected to SFP port) that was the issue.

Thanks for the help!