VM 50mbit - Wired vs Wiress vs 2.4ghz vs. 5ghz

[systematic]

Got a problem.

I have the DLink DIR-855 router that has been set to operate in dual frequency mode. Both frequencies (2.4 and 5.0ghz) work fine.

The problem is the speed on wireless compared to wired from the router.

Wired speeds from router - 50mbits no sweat.
Wireless speeds from router operating in 2.4ghz - approx 20mbit
Wireless speeds from router operating in 5.0ghz - approx 11mbits

Everything is set properly - N mode and the PC I am using the 5.0ghz frequency is using the offical Dlink 5ghz dongle (DWA-160).

One thing to notice is that everything was working sweet as a peanut last week. Both frequencies could get 50mbits.

Wireless N is selected, Channel is set to Auto (best-automatic), 40mhz has been set for 5ghz frequency setting, TCPIP optimiser has been used on all adapters. I am using a box running Windows 7 X64 with 8gb RAM.

I am just setting up a virtual OS within Windows 7 - Windows XP. I will check if there is any software conflicts that are causing the slow speeds via Wireless in Win7.

Any suggestions or advice would be great?

Thanks,

[AbyssUnderground]

Set the channel manually. Never use 1, 6 or 11. Use something inbetween, as 1, 6 and 11 are default channels and as such are subject to the most interference.

Got any wireless phones or new gadgets recently that could interfere?

Also what encryption are you using? That does make a huge difference if you've changed it.

If it WAS working, then TCP Optimiser will do nothing, and it doesn't work on Vista/7 anyway. Something else is wrong if it just suddenly drops.

What about firewall/antivirus? They can also make a difference by slowing down packets due to real-time scanning.

[systematic]

Ok same speeds in XP.

4 - 11mbits, with no software. The only thing in XP is the software built-in firewall.

I have also tried to disable wireless encryption on both modes and still nothing decent.

The encryption used for both modes is WPA2-Personal AES.

I think this has to do with the Routers firmware or something.

[AbyssUnderground]

Forgot to mention the all important router reboot too.

[systematic]

Forgot to mention the all important router reboot too.

Done that about 20 times. Im gonna reboot and reset to factory defaults and see what happens.

---------- Post added at 20:05 ---------- Previous post was at 19:57 ----------

Ok router set to factory default - no secuity, nothing.

Still CACK speeds.

[systematic]

Update.

Tried a different wireless adapter (2.4ghz supported ONLY).

Connected, did a speed test and got a lovely and consistent 51mbit speed test.

Looks like the culprit was the gay Dlink DWA-160 in 5ghz mode.

[jrhnewark]

Makes sense that 5GHz is awful if you're not in line of sight of the router... it'll just not get through the walls the same as 2.4GHz.

[systematic]

Nah, had nothing to do with line of sight. The 5ghz adapter was in the same room as the router in perfect site with no environmental factors in between. The router and adapter were 2 metres apart.

I think it just gayed out on me.