Posted: Sat Apr 04, 2020 14:40 Post subject: [Solved]Archer A7 slow throughput on Comcast but not Verizon
Hi folks, I have two TP-Link Archer A7 routers flashed with DD-WRT v3.0-r42729 std. I get my full 100/100 speed when connected to Verizon FiOS, but I cannot get the one connected to Comcast business any faster than 15/5 even though I have a 200/50 plan. SFE and STP are disabled. MTU is set to auto. Both accounts are static IP. I've swapped both pieces of hardware and the one connected to Comcast is always capped at about 15mbps. I can pull 60mbps from the Comcast account with a WRT-54GL with DD-WRT v24 SP2, and get my full 200 speed when connected directly to their modem, so they are delivering full speed to the modem. The wireless radios are turned off on both units as we have UniFi systems at both offices. My speed tests are done when connected by an ethernet cable to the router. Any suggestions on what setting(s) I need to adjust?
I have been using DD-WRT with WRT-54G routers since about 2006. I have 20 of them serving faithfully at various branch offices. I am phasing out the Linksys models because they cannot give me full bandwidth with todays high speed connections. Otherwise, they've been very stable, with some units going well over a year without being restarted. Usually, a power failure long enough to drain the UPS is why they restart, not because they locked up.
I am trying to find a suitable stable, affordable replacement. These TP-Link Archer A7's are my first, although I doubt they'll be available for as long as the one that started it all.
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Sat Apr 04, 2020 15:16 Post subject:
Comcast is most likely limiting your speed because they are seeing two different Mac addresses using the same modem. That means you will need to reboot your modem and see what happens. if you still don't get full speed after rebooting the modem then the next step to try would be to spoof your Mac address on the Archer A7 and see what speeds they give you then.If magically when you spoof your Mac address on the A7 from your older router and your speeds go up then it means that Comcast is limiting your speeds because of dual Mac addresses being found on the network. If that's the case, you may need to call them or run a spoofed MAC address from here on out. I have Comcast here, and a simple reboot of the cable modem resolves that Mac address issue when I switch routers up. _________________ FORUM RULES
Thanks for the response. I will get the Mac address out of the old Linksys and have the A7 spoof it and we will see what happens. The next step is to call Comcast support and have them reboot the modem remotely. I am about 40 miles from that branch office at this point. FWIW, there are two other devices hooked up to the modem. A WRT-54GL that is the router for the corporate network and a Peplink VoIP gateway for our IP phones. The Archer A7 is the router that feeds our guest WiFi system.
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Sat Apr 04, 2020 16:00 Post subject:
You should be able to hop online to your online Comcast account and reboot the router through the support pages of your account. I don't recall which one it is off the top of my head, but I do know that you can do it yourself. _________________ FORUM RULES
I remembered that the first thing they do is restart the modem remotely if you call with an internet problem. I did that and they restarted their modem. I am getting the same dismal speeds. I'll pull the old Linksys from my car, get the Mac address and try that.
Could this possibly be a problem with the WAN port settings? I remember that Comcast was adamant about manually setting our equipment to 1000 FDX when connecting to their Fiber EDI equipment, or we would not see full speed. But that's a totally different ball of wax. Thanks again for the response!
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Sat Apr 04, 2020 16:28 Post subject:
You might need to restart the modem without the router hooked up first, which means you need to be there in person to do it... _________________ FORUM RULES
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Sat Apr 04, 2020 16:56 Post subject:
It also could be Comcast business is more strict with the IP lease and you need to call them and have them reset a lease under a new Mac address.... My only experience is with home services on Comcast. Though I can't imagine business class would be any different other than the price gouging... _________________ FORUM RULES
The Mac address spoofing didn't help. We have static IP addresses and a block of 5 addresses of which three are in use. I even switched over to a different WAN IP with no change. I'll visit the site on Monday to reboot the modem with no equipment connected and try again.
As far as Comcast business goes, yes we pay more, but we get a higher level of service. If our internet goes out and it is their system, they'll get someone out the same day to fix it. Much better than their residential service, where you may be out for a couple of days or more. Same with Verizon business accounts. Thanks again.
I just got off the phone with Comcast support. They say everything is OK and that the problem is with my equipment. I ran "swconfig dev switch0 show" in the command line interface and it returned:
Port 0 is the WAN port I am assuming and it is showing up differently than port 1, which is the connection to my switch. What is the difference between "full-duplex txflow rxflow" and "full-duplex auto"? Could this be an issue?
Anyone else have any ideas as to what may be going on? I know the router is capable of much higher speeds, as it worked well when I tested it at my office on Verizon FiOS.
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Sun Apr 05, 2020 3:22 Post subject:
You may want to wait until on site and perform a factory reset via telnet/ssh using "nvram erase && reboot" and start over.
Sometimes goofy gremlins lurk around and a reset is necessary...sometimes a remote update goes wonky and a hard reboot of the router is necessary too.... That was the case for me on my Netgear R9000 last week on one of the builds.
Is it possible you set qos, and, input low values?
The GUI expects kbps and not Mbps so 100mbps is actually 100000.
That's about the only other thing I can think of.
My A7v5 outputs the exact same thing on my swconfig dev switch0 show. So your's seems to be ok. _________________ FORUM RULES
I know I just need to be on site to do some real troubleshooting, but this is really bugging me. I got two Archer C7's from Best Buy yesterday. The C7 is the model I originally wanted, but Amazon took me to their A7 model when I did a search. Bastards. I don't set QoS at the router, I set any throttling using the UniFi software. I'm flashing one of them now and will leave the other with the stock firmware for comparison. Thanks for taking the time to compare those results!
FWIW - I did set QoS for 5000kbps and it did throttle down to 5mbps - then I turned QoS off and it went back to 15mbps. So QoS seems to be working properly.
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Sun Apr 05, 2020 16:16 Post subject:
Maybe Comcast business class is expecting a certain VID for the wan port? Seems strange and unlikely, but anything is possible.
Again, I only ever have done Comcast home use, but I can't imagine their business network working different how it assigns IP addresses to a cable modem. That I said, what kind of cable modem are you using?
Is it possible you got a bad ethernet cable in there? _________________ FORUM RULES
It wasn't the router at all. I plugged in a stock C7 and got the exact same speeds. Rebooted modem - same thing. I called Comcast again and once again, they claimed nothing was wrong with their equipment. I told them it was impossible that I have three defective routers so they sent a tech over. The tech looked things over and observed the same problem I did. Then he logged into the modem and found that QoS had been enabled on a few of the ports - set to 15/5. He explained that the modem was likely 'refurbished' before it was installed at our building and that the previous customer had enabled QoS and that never got cleared before being redeployed. I am now seeing the speeds we are paying for. And now the guests can stream higher quality video in their rooms. My luck that I plugged the new equipment into a port with QoS enabled.
The Comcast business modems are actually pretty nice. They have an 8 port gigabit switch with PoE+ and no WiFi to worry about.
Joined: 21 Jan 2017 Posts: 1783 Location: Illinois Moderator
Posted: Mon Apr 06, 2020 19:12 Post subject:
So my hunch about qos was correct, it just wasn't set on your router Lol, it was set on the modem... I've never seen a modem that actually allows you to set qos settings... I'm curious to know what modem that they're using.obviously there's a difference between the business class versions and the home use versions. I'm sure there's a secret menu somewhere in my Motorola sb8600 that I could have access to. _________________ FORUM RULES
Yep - QoS set at 15/5 and bullseye accurate traffic shaping!
This particular modem was installed after we upgraded the internet speed. The old one looked like a consumer-grade unit and couldn't do anything over 100mbps according to the tech. The new one has 8 gigabit ethernet ports with PoE+ and 8 RJ11's for analog phones.
