Solved AC87 vs Gigabit broadband

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Sky

Regular Contributor
Hello, Everyone!

I recently upgraded my broadband to gigabit over coax with Comcast (982/35 download/upload) and am seeing some issues. Hopefully wiser minds will point me the right way…

I have coax coming into the building from my ISP's branch box about 60' from the modem. When I connect a desktop directly to the modem via Ethernet I get Comcast's gigabit: 949.31/40.84 & 949.54/42.14. Reconnecting the desktop to the structured wiring which passes through a Gb dumb switch and out to the router I get basically 500/40. I excluded the building and switch from the group by wiring the desktop directly to the router and saw the same result, 500/40, so now I'm confident there is something about my RT-AC87R (aka: RT-AC87U) that is amiss.
  • The AC87 appears to be capping the WAN-to-LAN download at roughly 500 Mbps ± 100Mbps;
  • The inside LAN and all Ethernet components are Gb; and
  • The AC87 handles DHCP for the LAN.
What I don't know is:
  1. Is this a known limitation of the AC87, i.e., gigabit WAN-in will be limited going out even through one of it's four built-in Gb LAN ports;
  2. Is the incoming WAN signal parsed in some fashion when exiting to the LAN;
  3. Is there some setting I can check or tweak or something; or
  4. Will I have to say goodby to my trusty 87 if I want Gigabit from the WAN through the LAN endpoints? << I really hate this option :(
Thanks,
Sky
 

ColinTaylor

Part of the Furniture
What firmware version are you using (382.52288)? Do you know whether hardware acceleration is enabled?

Tim's review got 750-800 Mbps out of it, but enabling certain features (or bugs) could reduce throughput.

What is your WAN connection type, PPPoE?
 
Last edited:

Tucu

Regular Contributor
Hello, Everyone!

I recently upgraded my broadband to gigabit over coax with Comcast (982/35 download/upload) and am seeing some issues. Hopefully wiser minds will point me the right way…

I have coax coming into the building from my ISP's branch box about 60' from the modem. When I connect a desktop directly to the modem via Ethernet I get Comcast's gigabit: 949.31/40.84 & 949.54/42.14. Reconnecting the desktop to the structured wiring which passes through a Gb dumb switch and out to the router I get basically 500/40. I excluded the building and switch from the group by wiring the desktop directly to the router and saw the same result, 500/40, so now I'm confident there is something about my RT-AC87R (aka: RT-AC87U) that is amiss.
  • The AC87 appears to be capping the WAN-to-LAN download at roughly 500 Mbps ± 100Mbps;
  • The inside LAN and all Ethernet components are Gb; and
  • The AC87 handles DHCP for the LAN.
What I don't know is:
  1. Is this a known limitation of the AC87, i.e., gigabit WAN-in will be limited going out even through one of it's four built-in Gb LAN ports;
  2. Is the incoming WAN signal parsed in some fashion when exiting to the LAN;
  3. Is there some setting I can check or tweak or something; or
  4. Will I have to say goodby to my trusty 87 if I want Gigabit from the WAN through the LAN endpoints? << I really hate this option :(
Thanks,
Sky
Have you tried doing the benchmark with Adaptive QoS and AIProtection disabled?. Also check that NAT acceleration is enabled.
 

Sky

Regular Contributor
What firmware version are you using (382.52288)? Do you know whether hardware acceleration is enabled?

Tim's review got 750-800 Mbps out of it, but enabling certain features (or bugs) could reduce throughput.

What is your WAN connection type, PPPoE?
I'm on v3.0.0.4.382_52288, but in all fairness Tim's review was on Wi-Fi and my issue is over Ethernet. The WAN feed to the modem is coax (RG-6), modem to the router is Ethernet.

When I wire modem-direct over Ethernet I get Gb. When I put the router in the loop I'm back to 500/40. I expect issues with Wi-Fi as a matter of course, but I thought the Ethernet side would be solid, and it has been until moving from 450/12 to 1,000/35. Having issues over hardwire just going into and out of the router has me flummoxed.
 

ColinTaylor

Part of the Furniture
I'm on v3.0.0.4.382_52288, but in all fairness Tim's review was on Wi-Fi and my issue is over Ethernet.
The part of the review I linked to was for wired connections. Part 2 had the WiFi figures.
 

Sky

Regular Contributor
Have you tried doing the benchmark with Adaptive QoS and AIProtection disabled?. Also check that NAT acceleration is enabled.
This may well be party of the problem/solution.

I disabled IPv6 Firewall, as IPv6 connection was disabled anyway and thought I saw a small pop, but I think that was more wishful thinking than anything.

Disabled AiProtection—meh. Disabled QoS & got 200-300MBps more speed on the spot. Whoa! Re-enabling AiProtection definitely caused a serious hit on the first test run but it quickly recovered in subsequent runs to a net-zero change from having QoS off.

So QoS is definitely part of the issue. With this speed I'm not so sure QoS would be helpful so it's staying off for now. Even so, I'm still short a bit at an average of (now) about 720 vs. 900+.
 

Sky

Regular Contributor
The part of the review I linked to was for wired connections. Part 2 had the WiFi figures.
Oh derp. I didn't read down far enough, can't blame my eyes for that one. Mea culpa

Based on Tim's review with QoS off it looks like I'm at the edge of the AC87's envelope. I'm very reluctant to turn off—and leave off—AiProtection as its logs appear to indicate having staved off a number of bad guys over time. So I'm glad my little test seemed to indicate its impact, once settled-in, is actually pretty minimal.

Nat acceleration is set to Auto (auto|off) with CTF enabled.
 

Sky

Regular Contributor
Thanks for the help ColinTaylor & Tucu, you guys nailed it! :)

Considering Tim's 2014 review of the AC87 when it came out I'm pretty sure this is as good as the 87 is able to do. My throughput and spikes seem to match his review.

My primary goal with the 1,000/35 speed bump was to increase upload speeds for remote VPN work and it's solidly increased that over 300% (I was getting 450-530 DL before the upgrade, but UL maxed at 12). The extra DL speed was really gravy, but it irked me that I wasn't getting what I had contracted for. Today the ISP finally got the ducks in their plant lined up, then it fell to me to locate the issues on my side. Now I can rest easy knowing what the issue is and what I'm willing to accept or determined to change. That buys me a lot more room—and time—to decide what's next in the great router game.

Thanks, again!
Sky, one happy camper.
 

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