I can't seem to find any online references that'll help me, so let's try you guys.

I have an 802.11g network. It consists of a NetGear WPN802 AP, a Sony Vaio laptop with builtin 802.11g (Centrino-based, or Intel 2200BG at any rate), and a Mac Mini with its builtin 802.11g (although it was installed after the fact). The AP is connected to my wired network via an older NetGear dual-speed hub, which is the only ethernet infrastructure at all.

The problem is that it's very, very, slow. There's no problem authenticating or getting an IP address or passing data. It never seems to actually cause an error of any sort. It's just very, very, excruciatingly slow. Okay, it's still faster than my internet connection, but trying to pass any sort of LAN data is an exercise in tedium. I can't stream any video, for example.

In tests, I've found that the best throughput I can get is about 3.5Mbps. I know I can't really expect 54Mbps, but that's nowhere close. The "Wireless Network Connection Status" window on the Vaio shows that it's connected to the AP at usually somewhere around 36Mbps, but even if I get it directly adjacent to the AP and get a connection reported at 54Mbps I still get less than 4Mbps throughput. Getting it closer does seem to increase the throughput slightly, though, from about 3Mbps to about 3.5. And I've tested with the same computer on the wired network and get a reasonable throughput.

Things I've considered include a bad connection between the AP and the hub, which is not something I've completely discounted. (It would be nice if there was more information available about that on the AP, and it's not a managed hub.) I've also considered interference from other sources, but nothing I do (like peg to 802.11g instead of auto-sensing, changing channels, disabling SSID broadcasts) seems to have any positive effect. (Occasionally I shoot myself in the foot.)

I had what now seems to have been the same problem with a different AP, too, although also NetGear. I was thinking at the time that it was a range problem, so I got the extended range AP, only to find the problem was the same. So it's not just a broken AP, unless both of them are broken.

(Just now I noticed that Windows claimed that the speed dropped to 1Mbps for a significant time while I was typing this up, but then went back when I reloaded a random web page. I assume it was just saving power as I'm on the laptop right now, and it's not plugged in. Also, I've watched it during a data transfer test and not seen that problem, only slow packet counts.)

What else can I try?

Change the channel?

I just now remembered to test speeds between the Vaio and the Mini directly. That is, entirely on the wireless net without going over the wired net. (Not that I know how that works in an AP environment: I suppose it's possible that the data's still going through the AP and a wired network problem is still causing problems.) Anyway, I just tested that throughput and it's better: about 7.4Mbps. Still not what I would expect it ought to be, but better.

I was just thinking that I should throw the two computers into an adhoc network and test again.

Oops. Thats what I get for not reading it properly. It could just be that you've got lots of APs nearby and no channel is good?

Thinking about it, somebody I know had similar problems where it would show a good connection but the speed was crap. He tried everything and in the end he tried swapping the Netgear AP with his old Belkin and the speed went back to what it should have been. The reason why he got the Netgear in the first place was because the Belkin kept overheating and crashing. I think he replaced them both with a WRT54GS in the end.

Okay, I just tested the mini to vaio throughput via adhoc network. Regardless of the range, it transmits at approximately 17Mbps. A lot faster than the 7Mbps I'm seeing otherwise. It still doesn't seem all that fast, though. Can one of you comment on the speeds you're seeing on your 802.11g network? I'm using "nc -vv -l -p 25001 > NUL" on the Windows side and "time nc -vv -w 1 vaio 25001 < /path/to/bigfile" on the Mac end. (You have to subtract one from the resultant time because nc's waiting one second for a response.)

There's a Windows timing utility in the free Windows Server 2003 Resource Kit Tools, which also work on XP. And here's a Windows version of nc.

Although it's not terribly scientific a measurement, I'm presently copying DVDs from my wife's laptop (*) to my file server. It's taking about 30 minutes to move 5GB, which is about 22 Mbits/sec. I suspect that the bottleneck is actually the DVD drive overheating. Anyway, my Linksys WRT54GS seems to go quite fast. There's about fifteen feet, one wall, and one full bookcase between the computer and the base station.

I've experienced some slowness in the past, and I was always able to solve it by changing channels. I know you've tried that, but you might sequentially try each different channel and see if you observe any difference.

(*) This was the result of paying a commercial ripping service to chug through my CDs and rip to Apple Lossless format. I got 45 DVD+R's back. My Mac's "SuperDrive" is DVD-R, and has weird errors on some DVDs, so I'm using the laptop instead.

22mbps is actually fairly fast for 802.11g. 54mbps is the signalling rate and the maximum throughput is half that. Add on overhead and you get about 22-25mbps.

So 17Mbps is a reasonable one-way throughput to expect, then? Can at least one more person with a wireless network they think is working well do some testing, please? If it comes in around the 20Mbps range, then I think that leaves my AP as the culprit somehow.

At the moment a widget I have running is reporting 1.5-2.0MB/s (so thats 12-16Mb/s) as I copy some junk over my WRT54G network with WPA from my fileserver to my Powerbook. Half a room, a radiator and a brick wall directly between me and the AP - its basically on the edge of range.

I find it quite reliable, running OpenWRT.

And, for the record, I temporarily completely disabled all encryption to test when connected through the AP again, since the adhoc network also had no encryption, and got no throughput improvement than when I had the WPA-PSK enabled.

Well, shit.

I tried upgrading my AP's firmware. Seems that it just came out. Then the Vaio could no longer maintain a connection for more than a second or two. So then I looked to upgrade the driver for the wireless card. Sony still doesn't have an update, but Intel does. So I upgraded to that and now I can connect again, and I get full throughput: about 21Mbps.

So thanks, folks. Now I just have to get past the wife being mad at me because I wasted the whole day dorking on the computer.

Double shit.

I take it back. I'm connecting again, and I'm up to about 5Mbps, but the test before was accidentally done while I was still attached via ethernet.

I had trouble with my wife's Vaio, and the neat little Sony 802.11 card we bought for it. I eventually decided the problem was the card itself sucked.

FWIW, it was the wired dual-speed hub that was the problem. I swapped it out (with a Cisco 2950G-48 -- nice to have spare $3500 switches lying around the office) and now I'm getting throughput well into the teens. Now I have to buy a new switch; they might notice that one missing.

The only common problems I've had with Cisco switches are failing ethernet autonegotiation and duplicate MAC addresses (which is easy to have happen when you have multihomed Sun equipment: "eeprom local-mac-address?=true", if that's the problem).

I'm not the one in charge of the switch, so I've just been trying to figure out exactly what the problem is. I first noticed that going from a different subnet to the subnet/switch in question was going at a reasonable rate considering it had to go accross the street on a shared 100mbs link and back. So, I plugged my workstation into the subnet and switch in question, started transfering the file, and got around 10kbs per seccond. Traffic to the outside world continues normally.

So, I fire up netcat to do some experimenting. Transfers to the machine from the local subnet go at 10kilobits/sec at the maximum, but transfers from the machine go at least 1megabytes/sec. Maybe it's just a bad cable, but I don't want to disconnect it as it's the machine hosting the central image I just posted.

So for the moment I'm giving up.

Matthew