Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have seen a lot of people complain online about their modems/internet speeds. I too have consistent problems with Comcast internet. However recently being involved with setting up new office internet rated at 100/100mbps from a different provider, I found out something which I hope people can shed more light on here.

With this other provider we experienced bad speeds as well. 10/50mbp vs the marketed 100/100mbp. However when we disconnected the Cisco/LinkSys router and connected directly to the modem we got the 100/100 speeds. We found that "duplex" speeds was the variable here. Using ethernet cable directly to the modem our networking settings showed full duplex. When we introduced the router back in it jumped back to auto negotiate for duplex. Even the other provider confirmed they hard set their lines for full duplex to provide consistent high speeds.

Last night I had what appeared to be a 2 hour outage. Restarting my modem (Ambit Microsystems Corp. u10c035) and router (D-Link DIR-615) over and over... in the end I was back up. At 10/10mbps. Louzy for Comcast Blast internet speeds right. So I connected directly to the modem and nearly fell off my seat. 110/10mbps. Wow! My router is auto negotiating duplex speeds as well. I assume this may also be related why I need to restart both devices at the same time and hope they "sync up" so I can have internet again. There has to be a better way?

So the questions are???

  • What is a better way? Get a router which I can set duplex mode to full vs auto negotiate?

  • What would that router be when most consumer routers are hard set to auto negotiate duplex?

  • Is this a common problem that no one has tackled on the consumer side with fast internet speeds requiring full duplex and most routers on the consumer market not providing for it? Even though their advertised speeds state 300mbps+?

share|improve this question
We found that "duplex" speeds was the variable here. What do you mean. If it is on auto neg. does it end up connecting as half duplex? What model linksys is used in your first problem. It could be it does not have the necessary WAN-speed for 100Mbps. – Rik Jan 5 '14 at 8:30
@Rik yes that is correct. Used LinkSys EA6300 - Rated for 1200 Mbps & has 4 Gigabit Ethernet ports. Not a cheap router either. Yet has no capability to force duplex. Runs like a dog (15/50 Mbps) yet advertised like its the best thing since slice bread. – TurbZ Jan 5 '14 at 8:40
When you connected the computer directly to the modem you say it connected full duplex. Was the setting in the network adapter also full duplex or auto.neg.? If it was full duplex could you try setting it at auto.neg. and see if it does connect full duplex? (or drops back to half, i.e. mismatch duplex) Even though the provides confirmed they set it at hard full duplex i wonder if that is really true. It would mess up a lot of systems and not provide consistent high speeds. Every router should have auto.neg. so would get a mismatch duplex. – Rik Jan 5 '14 at 10:24
BTW for you D-Link DIR-615 you could use DD-WRT. It has the capability of setting the WAN-port to hard full duplex. You could try that router (with DD-WRT flashed) with the other internet connection to see if it helps. (if it helps in your own case of course) – Rik Jan 5 '14 at 12:11
Under ethernet it shows auto neg and duplex grayed out at full. Manually setting at full duplex I get = 120/22 mbps, half-duplex = 70/22 mbps, and back on wifi now getting = 9/9 mbps. What a massive difference! Could it be that Comcast Burst line is hard set at full-duplex? Anything else yields packet loses and a degraded performance. – TurbZ Jan 6 '14 at 8:09

You should to speak to your ISP to get your problems sorted out - the problems - from what you describe - appear to be a lack of compatibility and communication between your ISP and you, or possibly you are using non-standard hardware for their setup ?

That said, if you get a Linux box and configure it as a router (or even a *wrt router), you should be able to control duplexing and negotiation using standard tools (mii-tool springs to mind).

share|improve this answer
ISPs don't listen or just palm support to countries that can only read predefined scripts. Not much help. Already tried last week. Re Linux yap good idea and also considered it but not ideal solution. Routers on the consumer market should live up to expectations. – TurbZ Jan 5 '14 at 8:09
You may want to consider that you come across as expecting the corporate world to provide you with top rate service while paying bottom price, and not owning your problems. You can find ISPs where you talk to someone with clue (I used to run one). Similarly you seem to expect a cheap (consumer) router to be continually tested by manufacturers half way round the world making thin markups on volumes - and appear to reject the idea of even upgrading a router to a community supported *wrt device, or paying for a corporate grade router. – davidgo Jan 5 '14 at 17:13
Sorry if I upset you @davidgo with my venting, but what you said is not true. I expect hardware marketed at X speeds to live up to expectations. With your experience I would have thought you would suggest a solution/option here vs pointing fingers back at the consumer. Maybe my frustrations are valid with ISPs. – TurbZ Jan 6 '14 at 8:10

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .