Mikrotik router limiting connection to 100 Mbps

RouterOS General
1

Setup:
ISP provided router, set up in bridge mode → Mikrotik router → PC and other hosts

ISP Router (as bridge): Kaon CG2200
Mikrotik Router: RouterBOARD 951G-2HnD (Allegedly capable of up to 1gbps)
Cable used to connect both is about 2m long and labelled CAT5E
Cables used to connect mikrotik router and hosts (my PC and my server, which is basically a 2nd desktop pc) are also labeled CAT5E
RouterOS version: 6.49.15
Mikrotik firmware type: ar9344
Memory and CPU usage are quite low on average: 100 MiB | 10% CPU

Problem:
My ISP gives me an asymmetric bandwidth of 300 Mbps download / 20-30 Mbps upload (note that I contracted this service today). After having the router configured into bridge mode, I plugged in my laptop directly to the router and effectively got 300 Mbps download. However, when I plugged in my Mikrotik router to the ISP router, and my PC to the Mikrotik router, speeds were consistently capped at 100-120 Mbps (both times tested both with speedtest.net and fast.com). After repeating the test with my laptop using the same cable that was used by the mikrotik router, it again reached speeds of about 300 Mbps without any issues.

What I currently have set up on the RouterOS:

  • Simple bridge between ether2, 3, 4 and 5
  • NAT masquerade rule for ether1
  • DHCP server for bridge
  • DHCP client for the WAN IP
  • Some NAT rules to port-forward a minecraft server, among other things
  • Some firewall rules to prevent incoming traffic from unknown ips on those ports
    Not a complex setup really

What I have tried:

  • Using another cat5e cable
  • Connecting the “WAN” cable to ether2 (still capped at 100)
  • Checked status of the ether1 port, auto-negotiation says the speed is set to 1Gbps
  • Tried to force 1Gbps both full and half duplex on ether1 (WAN), connection stops working (weird)
  • Used iperf3 to measure transfer rates on the LAN. Gets to 900+ Mbps
  • Connected router directly to my desktop PC, gets to 300 Mbps

Honestly I’m out of ideas. I am still fairly new to RouterOS and networking in general, but I have already spent hours trying to fix this. Everything seems fine except the fact that I can’t force ether1 to use 1Gbps, but I know the cable can comfortably reach speeds of over 300 Mbps

2

Fixed by enabling fasttrack running these commands from the Mikrotik FastTrack manual page:

/ip firewall filter add chain=forward action=fasttrack-connection connection-state=established,related
/ip firewall filter add chain=forward action=accept connection-state=established,related

https://wiki.mikrotik.com/wiki/Manual:IP/Fasttrack

3

Two things:

  1. many of MT’s small routers can’t route at wirespeed. So if a device has 1Gbps ethernet ports, it doesn’t mean it is capable of routing at this speed. official test results (linked for RB951G, but these are available for all devices) indicate[*], that this device is realistically capable of routing at 250Mbps (give or take, highly dependent on actual config … not only firewall filter rules, but also other things, like WAN technology - PPPoE tends to reduce throughput quite a lot)
    [    *] experience around this forum goes, that most real-life relevant number in test results table is the one listed under “Routing → 25 ip filter rules → 512 byte packet size” … but depending on actual device config it might be -50% or +100%.
  2. factory default config includes fasttrack enablement rules. So if your config at time of writing opening post didn’t have it, this means you changed default config without thoroughly understandind what you were doing
4

Standard user: I don’t know how to do it / I modified it = RouterOS bug

5

nice, work for me on my RB2011UiAS-2HnD

getting stuck at 100Mbps, now it got ISP speed 200-300Mbps

6

If the speed is more or less exactly 100 Mb/s, then my money is on this being an autonegotiation failure. In Webfig [Interfaces → ether 1] scroll down to Ethernet and look inside at the permissible speeds.

I think the Routerboard is discontinued and the software version is quite old, so the defaults may be more in keeping with an earlier age.

7

If the speed is more or less exactly 100 Mb/s, then my money is on this being an autonegotiation failure. In Webfig [Interfaces → ether 1] scroll down to Ethernet and look inside at the permissible speeds.

I think the Routerboard is discontinued and the software version is quite old, so the defaults may be more in keeping with an earlier age.

This issue is solved, the problem was that there were no rules for fasttrack