DD-WRT speed issues

[Jhaedee]

So as the title suggests i've got some problems with my network setup that have only recently come to my notice.  In the last few months i've been using my Virgin Media Superhub 2ac in modem mode to provide my dd-wrt router with a connection and then our devices are provided wifi by the dd-wrt.  For some reason speedtest and general downloading is consistently only around 60mb for download when connected this way.  However, as we recently got Virgin 'VIVID' 200mb connection as a free upgrade I'm quite disappointed by this.  So i set the Virgin Superhub back into router mode (as opposed to modem mode) so it's providing wifi to the house again and when I did this and did the same speedtest/downloads I got over the advertised 200mb on average (usually between 202-206).  This wouldn't be an issue for most people but in this circumstance the dd-wrt router is  necessity as my mobile doesn't do well at the back of the house with the virgin superhub and equally the superhub doesn't have sufficient settings for me to use unlocator.

 

I'm wondering if there is some kind of setting or something else relatively simple to explain the loss of 140mb of speed.  Any ideas?

 

Many Thanks

[xendrome]

So, what router make/model do you have?

[Jhaedee]

My bad.  That would be helpful wouldn't it.

 

It's  this one - TEW-811DRU

[xendrome]

Latest firmware? Make sure QOS is off in settings

[Jhaedee]

33 minutes ago, xendrome said:

Latest firmware? Make sure QOS is off in settings

QoS is disabled on the NAT/QoS tab and the firmware version is listed at the top of the screen as but i'm not sure how to search for updates?  It advises me the firmware that is running is 'Firmware: DD-WRT v24-sp2 (03/27/14) std' which doesn't sound very up to date but then again I only started using dd-wrt and this router in Sept 2015 so i'm guessing it was up to date at the time.

[RandPC]

DD-WRT doesn't (and can't) support hardware NAT. Doing it in software is much more demanding on the CPU so given the hardware your router has 60mb/s seems pretty reasonable. Unfortunate trade off of all the options DD-WRT provides.

If you don't need the extra functionality then you should be able to get better peak bandwidth by flashing back to the stock firmware. Otherwise, if you really need DD-WRT then a more powerful router will get you closer to 200, although I doubt you'll get all the way there with any consumer level router. The hardware in your router is pretty weak, so a better router could definitely offer much more. Overclocking the router's CPU is also an option but at a quick glance reviews indicate your router runs extremely hot at stock so it's probably not a good option in your case.

If getting a better router isn't an option then I recall there were some performance improvements on Broadcom based routers in DD-WRT circa early 2015 so you may want to update to a more recent version of DD-WRT, that's likely only going to be small gain at best.

[Jhaedee]

39 minutes ago, RandPC said:

DD-WRT doesn't (and can't) support hardware NAT. Doing it in software is much more demanding on the CPU so given the hardware your router has 60mb/s seems pretty reasonable. Unfortunate trade off of all the options DD-WRT provides.

If you don't need the extra functionality then you should be able to get better peak bandwidth by flashing back to the stock firmware. Otherwise, if you really need DD-WRT then a more powerful router will get you closer to 200, although I doubt you'll get all the way there with any consumer level router. The hardware in your router is pretty weak, so a better router could definitely offer much more. Overclocking the router's CPU is also an option but at a quick glance reviews indicate your router runs extremely hot at stock so it's probably not a good option in your case.

If getting a better router isn't an option then I recall there were some performance improvements on Broadcom based routers in DD-WRT circa early 2015 so you may want to update to a more recent version of DD-WRT, that's likely only going to be small gain at best.

Ahhh right, I kind of understand now.  The only thing that still confuses me is that you said I wouldn't get close to 200 with a consumer level router but the virgin media superhub 2ac is just that, a consumer grade router and it can manage 200-206 with no issues.  And from the reviews of it that i've read, it's supposedly pretty poor hardware. I guess I could ditch the unlocator service etc but then i'm still left with the issue of the reception at the back of the house

[RandPC]

4 hours ago, Jhaedee said:

Ahhh right, I kind of understand now.  The only thing that still confuses me is that you said I wouldn't get close to 200 with a consumer level router but the virgin media superhub 2ac is just that, a consumer grade router and it can manage 200-206 with no issues.  And from the reviews of it that i've read, it's supposedly pretty poor hardware. I guess I could ditch the unlocator service etc but then i'm still left with the issue of the reception at the back of the house

The Virgin router, using stock firmware is almost certainly capable of hardware NAT. That's the key difference between it and your other router using DD-WRT. Not being capable of hardware NAT makes it much harder to push a lot of bandwidth down.

ie. my router with DD-WRT I can push about 120mb/s at stock speeds, overclocking my router I can push about 135. If I were to flash back to the stock firmware I could hit 200 with ease since the stock firmware allows for hardware NAT. When the processor has to do all the work by itself as is the case without hardware NAT it's much more difficult.

DD-WRT is absolutely awesome and I love it, but it's never going to be able to push the sheer bandwidth numbers of the manufacturers firmware.

[+Fahim S. MVC]

Random question, but is the connection from the 'modem' to the 'router' definitely operating at gigabit speed?

 

[Jhaedee]

7 hours ago, Fahim S. said:

Random question, but is the connection from the 'modem' to the 'router' definitely operating at gigabit speed?

 

How would I tell?  I believe it states on the product websites that its ports are gigabit speed