Debugging slow internal router with Hitron CGNM-2250

[reillywood]

I upgraded my speed yesterday to 300/30 from a measly 25/2.5. Now I'm trying to debug why my own router (using IP Passthrough) is limiting the download speed to about 100Mbps. It's an archer c7 v2 running about a 2y old version of dd-wrt, which has been fine up until this speed change identified this problem. If I connect to the cable modem, I get about 300 down. If I connect to the dd-wrt router, I get about 100 down. In both I get about 15 up.  I get these same results if I connect by wire or wireless.

The cable modem is connected directly to the outside cable line. The dd-wrt router is connected to the cable modem by a 40 foot cat 5e cable. QOS is turned off.

I've played around with several variables so far but none yet change the result.  Next up is to bring the router closer to the modem to test the cable length as the cause.

1. I've tried connecting to my router via wired and both wireless (2.4 and 5Ghz)
2. I've connect with 801.11n and .ac
3. I've tested wifi from just a few feet away from the dd-wrt router
4. I'm confident network volume (internal and external) isn't an issue. Internally, very little is going on. Externally, I can swap between the hitron and my dd-wrt router at will to see the difference
5. As far as I can tell, the hitron and the dd-wrt router ports are operating at 1000Gbps

What else could be the problem?

Thanks in advance for your help.

[reillywood]

Further testing has found that my problem is with the dd-wrt setup.  I reset to defaults and I get full download speed of 300Mbps.  

[mdk]

> I reset to defaults.

I'll take a guess that a complete power-off/power-on of your device would have fixed it -- that would have been less drastic than a "full reset".

[reillywood]

That could be the case.  But I had rebooted it several times before the reset and saw no difference.  However now, though the reset did improve things in some scenarios, other scenarios are still very low download speeds.  Upload speeds are interestingly always at or near 15Mbps.  Wifi distance is a factor, Wifi frequency appears to be a factor (2.4 is often better than 5 maybe because of walls).  And I suspect the length of the cat5e could be impacting things.  Testing continues.

[mdk]

>  other scenarios are still very low download speeds.

Qualitatively, you have said "very low".  Can you be quantitative? Actual speeds? Your hardware?

To get maximum download speeds:

* Ethernet CAT-5e or CAT-6 cable -- not CAT-5, which is certified only to 100 Mbps,

* not-overly-long length of Ethernet cable,

* avoid WiFi network adapters that cannot do 300 Mbps,

* Ethernet network adapter in your computer that is 10/100/1000 -- not just 10/100,

* Ethernet network adapter that is configured to "auto" speed-negotiation, not a manual setting of 10 nor 100,

* dual-core CPU at more than 2 Ghz -- slower computers cannot run Shaw Speedtest at its full speed -- you get lower results.

I think that you already know all this.

[reillywood]

Thank you @mdk 

I'm pretty sure it's cat5e that I'm using, but I haven't physically checked it yet.  It's about a 40 ft cable, possibly running next to some electrical cables though.  

The same hardware (laptop, dd-wrt router) all perform well at some points in time (i.e, at or near 300Mbps download) so I assume from this the adapters (wifi & ethernet) are capabable of >100Mbps.  And all the laptops are at most 3y old lenovo T450/T480S multi-cores.

Speeds I have gotten so far:

1. T450 directly connected to the cable modem (by ethernet or wifi 2.4 or 5Ghz):  ~ 300 down / 15 up
2. reset dd-wrt router connected via 2 foot cat5e cable to the cable modem, T450 connected to dd-wrt via ethernet or wifi (2.4 or 5Ghz): ~ 300 down / 15 up
3. dd-wrt relocated to longer cat5e cable and laptop connected via wifi through about 3 walls: ~50 down / 15 up on 5Ghz and ~75 down / 15 up on 2.4Ghz

Later today I'll connect to the dd-wrt via ethernet and see what speeds I get, and I'll check on the longer cat5e cable.  

[rstra]

Could be some interference in the wall with the cable. Obviously, your equipment is capable of those speeds, any desktop newer than about 15 years old is capable 😀

Have you tried a connecting direct to your modem using the cable in the wall?

[reillywood]

Good idea.  I'll try that this afternoon.

[reillywood]

So, using the same cable that the dd-wrt router uses, I get close to 300 Mbps down.  

When I reconnect the dd-wrt via the cable, reboot, and retest through the router (tried both wifi 2.4 and ethernet) I get about 90 Mbps.

Seems to be something with the router itself.  Next up will be to try a later version of dd-wrt.

[rstra]

“Next up will be to try a later version of dd-wrt“

Probably easier than rewiring. Let us know how it goes.