Before reading further, please note that this thread is quite long and if you're short of time, skip ahead to the last sentence.
About 5 days ago I purchased a D-Link DGL-4300 router and I've encountered a number of problems due to it.
So after attaching the wireless router to my desktop PC and DSL modem, I immediately lost internet capabilities. Being a novice when it comes to routers, I ran through all the content offered on the D-Link CD disc in the router box, but couldn't get my internet back. Of course, I did some troubleshooting of my own. Restart computer. Unplug router, 20 seconds, unplug modem, 20 seconds, replug modem, 20 seconds, replug router. Didn't work. I then replugged the modem cable back into my computer, completely removing the router as a factor and my internet was restored.
At this point, I'm a little frustrated. I decide that my ISP is not at fault and contact D-Link technical support. They do some troubleshooting and discover that my router and modem are sharing IP numbers and they fix it by changing the IP number for the router. There was a conflict between them, apparently. The internet for my PC is restored, so I think it's done so I go to bed.
Next day I get home from work, load up my laptop and try to access the internet. Can't get it to work. My PC still works fine, but my laptop can't maintain a connection at all. If I reboot the router, it would usually work for a while, then quit. So I call up D-Link again, get a new person and they end up telling me that the reason it's doing that is because I need a static IP and that I'd need to call my ISP to "bridge the connection" between my modem and router. Okay. I call my ISP, AT&T, tell them the situation and they're seemingly familiar with the situation and tell me that my D-Link router, the DGL-4300 specifically, already has this functionality built into it. Okay, my patience is burning low, so I play with my router settings more. I find areas of my administrative login for me to put in a static IP, but it warns me that I'd need information from my ISP, numbers only they can provide. I call them again, tell them the situation and they say that I don't need to put in a static IP because it's unnecessary and costly. Instead, they give me some general tips such as modifying the channel and putting it on 11. Having got nowhere with that call, I hang up. The final call I've made was to D-Link again, which also went nowhere as they really couldn't help me. The only information they were able to provide the last time I called was that I should upgrade my firmware and if the problem persists, to exchange my router in for a new one from where I purchased it. Let me say here that the firmware did not help me.
This is the situation I'm in at this point. Having spent several days with the problem now, I feel that I can describe it fairly accurately. For my PC and laptop, my internet works, but every 10 to 15 minutes I will briefly lose internet. When I say brief, I mean very, very brief. Not long enough to notice if you're browsing the web, but extremely obvious if you take part in the actions described below.
1. Use VoIP software on your computer. I run Ventrilo, which is a VoIP application for communicating. It takes low processing power and bandwidth, so 80% of the time, it's running. I use this application to speak in real time with friends and associates. With the router plugged in, I get booted from Ventrilo every 10 to 15 minutes, like clockwork. The reason I get booted is because my internet goes down for a second, which causes Ventrilo to disconnect. I can typically log back in, but let me tell you it's nothing short of frustrating. I will also receive an error something along the lines of; "duplicate IPs not allowed", which got me to thinking on the situation.
2. Like to download things. If you're doing a straight download, it'll get killed off. I think this also has an effect on programs such as uTorrent if you're downloading bit torrents. I'm pretty sure it did for me.
3. Play video games that utilize a patcher. For example, many MMORPGs on the market and certainly other games and applications, will use a patcher utility. When you run your application, it'll first load a patcher which scans your files and provides you with an update for automatic downloading. So, if you have a 3 hour download and your internet goes down every 15 minutes, that takes a lot of micro managing.
Just in the last 5 days, I've spent an enormous amount of time speaking with D-Link and AT&T technical support, micro managing my patcher downloads, torrent downloads, ventrilo problems and general DGL-4300 settings maintenance. I'm extremely frustrated. To the point where I simply did a google for router help and found this. I'm venting. I'm angry. I have no idea why it's doing this and I've called technical support 5 times, gone through their stupid procedures 5 times and they're all at the point where they've expended their options for helping me. I'm about to return the damn router and be done with it. I guess this is pretty much my last attempt at resolving the issue. So, if anyone here has experience working with routers, specifically D-Link or even better, the DGL-4300 router, I'd greatly appreciate some assistance. I'll close this thread with this post summed into a single sentence question.
Why would a router cause my computers, my plugged-in PC and wireless laptop to briefly lose internet for a couple seconds every 10 to 15 minutes without fail and how can I resolve this?
First, the problem you're describing shouldn't happen with a router. As it doesn't occur when a PC is directly connected to the modem we'll have to conclude the issue is caused by the router.
The question is whether the router is doing it on the LAN segment or the ISP segment (the modem is attached to the grey port, not one of the orange ports, I'll assume).
Most likely the problem is the LAN segment as you get duplicate IP address notifications on the PC. You can fix this easily by turning off the DHCP server in the router, assign IP address 192.168.1.1 with subnet mask 255.255.255.0 on the LAN, then assign the PC 192.168.1.2 with the same subnet mask and finally the laptop can be given IP address 192.168.1.3, also same subnet mask.
If the problem stops then you know the problem was the DHCP server in the router was assigning duplicate IP's. This is abnormal behaviour, but can be caused by duplicate MAC addresses (check your PC's and laptops MAC addresses, if they are the same, that is the root cause).
If the problem remains the router doesn't properly update it's DHCP lease from your ISP. A static IP can fix this, but that's not an option. Some routers can be told how often to renew their lease. If you can and it happens roughly every 10-15 minutes set it to renewe every 5 minutes. Don't go too low on the renewal as some ISP's will block you if you renew too fast over a prolonged period.