Slow Ethernet between hAP ac and SB8200

RouterOS General
1

This issue is puzzling me and I’m struggling to figure out where the slowdown is coming from.

For starters:

  • Arris SB8200 Modem
  • RB962UiGS-5HacT2HnT hAP ac router
  • ROS 6.43.4, Firmware 6.43.4
  • 1Gb/s down - Comcast as ISP
  • PC connected to eth2 on the hAP with the modem on eth1.
  • Very basic setup no NAT rules other than masquerade, fast tracking established / related on the forward chain, no mangle or raw rules.

Currently I’m getting an average of 300 Mb/s down, I’ve seen as low as 180 and high as 560, but it’s inconsistent. The hAP’s CPU is showing around 30-40% use during the speed tests. Profiler shows networking / ethernet next below cpu0 with neither really breaking 10%. Confirmed the interface is showing 1Gb/s Full Duplex.

If I connect my PC direct to the modem I pull full advertised speeds and get around 960 Mb/s with the ethernet overhead.

If I connect a second PC to eth1 and have it act as a WAN (give out a DHCP address to the hAP which it then NATs to PC1 on eth2) and run a speed test between PC1 and PC2, I’m getting ~960 Mb/s with CPU hitting 80-90% use. No settings changed at all from when it was hooked up to the modem on eth1. Used the same cable from eth1 to PC2 as I did from eth1 to Modem.

Connecting PC2 back to eth3 I get full wirespeed between PC1 and PC2 with almost no CPU use as expected since it’s handled in the switch.

If I turn off DHCP client/server, plug modem into eth4 and just grab the modem’s DHCP from my PC (trying to use the hAP as a switch like above) I see the same ~300 Mb/s.

Any ideas on what is going on here? Something is just not playing nice with the connection between the SB8200 and the hAP and I can’t seem to track down what it is.

2

More confusion.
Grabbed a decommissioned RB1100AHx2 from the office and hooked that up to test. Same results, 250-300 Mb/s download speeds, this time barely scratching the CPU with less than 10% on either core.
Not even sure where to go from here, seems there is just something about ROS that the SB8200 doesn’t like.

3

Did you ever figure out the problem? I’ve got exactly the same issue. I have the same modem connected to a Microtik Cloud Router. Can’t get more than 400Mbps from computers connected to the router, but if I go directly to the modem (SB8200) I get 920Mbps.

4

Never did end up figuring it out, I picked up an RB4011 and that is able to run at full speed. If you’re using a CCR with the same issue then I wonder if the ARM CPU is the difference maker or something.

5

I have the RB450Gx4, very similar to the hapac2 and I have no issues grabbing the full 1gig service from my ISP?