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I have a D-Link DIR-825 router and for some reason it is blocking one of the wired desktop computers from accessing Internet, while it still allows it to communicate with other computers in the LAN. And also, those other computers can access Internet without any problems. What's going on here?

I tried flashing the DIR-825 with the same firmware version 2.01EU. And then I load my settings from file. And it's the same thing again. I also tried with 2.06EU which is some mystical firmware version that is not published on any of the official D-Link websites but is available from the router interface when you check for new software. But this one didn't help either.

Also, one very strange thing is that this stupid box seems to remember the settings, even after you flash it with a new firmware. After flashing it gives the IP to the desktop computer. This is the IP I had reserved for this computer. But this is before I even have restored my settings. So it appears to remember the old settings even after a flash process and even without loading old settings from file. Why is that?

Also, what file or files do I need to flash it with the DD-WRT router firmware?

share|improve this question
Are you sure the router is to blame? If all devices but one are working, I'd take a closer look at the one device. Is that desktop getting the correct DNS settings from the router via DHCP, or possibly is the desktop holding onto its own (incorrect) DNS settings? – trpt4him Jan 6 '13 at 22:23
You would think so, yes. But there is nothing wrong there. The PC obtains the IP and the DNS from the router. The router obtains the IP and DNS from ISP. I have also checked MAC filtering (network filter) which I have been using, and this computer was added to the list of allowed devices. So nothing wrong there. It's just a crappy router with crappy FW, that's my best guess. – sammyg Jan 8 '13 at 21:43
up vote 1 down vote accepted

I suggest resetting the device, that is, completely clearing the configuration and starting from "factory state", either by the reset button on the back or by the software option. The old settings from before the flash may not be compatible with the new firmware. On the routers I've used (D-link, Linksys, and a generic one) they explicitly warn you that settings files from previous firmware versions are not valid after a flash. They may have forgotten that this time.

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Yes I think I have seen a remark about that somewhere. And it makes sense, really, if you think about it. But it would have to depend on how much different the new firmware is. But the thing is, even if I use the same FW version, like 2.01EU over and over again, it doesn't matter. It still remembers the old settings, before I even restore the settings from a previously saved file. So it has nothing to do with upgrading the FW, that's irrelevant. – sammyg Jan 6 '13 at 21:07
I have read on the DD-WRT website that there is a "30/30/30 procedure" where you hold the RESET button on the router for 30 seconds with power on, with power off, and with power on again, before releasing the button. This is required for installing things like DD-WRT. This procedure is supposed to do a hard reset of the router. I might try that trick, even if I don't flash it with DD-WRT, just to make sure that all of the old stuff is completely cleared out. And I will then set the settings manually one by one, without loading them from file. – sammyg Jan 6 '13 at 21:10
You were right about "factory state". That did help. But the way to get there is not very obvious. Because the router pretends to reset default settings when you press the RESET button and they don't appear on the web interface no more, but the settings are really still kept internally. All it does is restore the password in case you forgot yours. So you would have to do the 30/30/30 procedure I mentioned. This is also the procedure you need to do in case you want to flash it with DD-WRT. See:… – sammyg Jan 8 '13 at 21:48

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