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[bballstuffer]

I have seen some members mentioned the same in other posts but I don't think we have a post dedicated to this problem. Basically between the primary and secondary 5ghz band, I am noticing a large difference in signal strength and unless I am standing right next to the 890L the primary 5ghz is so weak it's barely used at all.

I have used all sorts of wifi scanning and analyzing tools and they all tell the same. For example, I was standing right beside the device and the primary signal is between -35dBm to -45 whereas my 2.4ghz and secondary 5ghz is at -25 to -30. And this difference remains basically everywhere in my house.

I first thought could be smart connect that screwing things up so I turned it off and manually adjust the signal strength of each band but is no use. Also, adjusting the signal strength of the primary band does not seem to have any impact on the dBm measured but the adjustments do impact the dBm measurement for the 2.4ghz and secondary 5ghz.

I don't think this is a problem isolated to my unit as I have seen other members mentioning the same in other posts. I am currently on v1.09 but I have tried with v1.10 and v1.11 and results are the same. My hardware version is A2.

[FurryNutz]

Link>Welcome!

I recommend that you phone contact your regional D-Link support office and ask for help and information regarding this. We find that phone contact has better immediate results over using email.
Let us know how it goes please.

[Hard Harry]

This sounds normal. 2.4Ghz has greater range because it's a lower frequency (just like lower frequency sound travels further) and greater wall penetration. Actually, I have never had a router where the two frequency are the same strength, even right next to the router. It's not that it's weaker, it just doesn't go as far.

[FurryNutz]

Depending upon building materials as well. However both 5Ghz radios should be about the same in signal.

[Hard Harry]

They should be broadcasting the same dB, but that doesn't mean the wireless adapter will receive the same signal. It's like someone whispering next to you in a high pitch voice or a low pitched voice. Same volume, but you hear the low pitch whisper better. Bottom line is if OP is looking for range, and the 2.4Ghz band isn't congested, they should use that.

https://www.howtogeek.com/222249/whats-the-difference-between-2.4-ghz-and-5-ghz-wi-fi-and-which-should-you-use/

[FurryNutz]

Well thats good however on the 890L, Smart connect is enabled and channelization and device connections are being handled by the router.

[bballstuffer]

This sounds normal. 2.4Ghz has greater range because it's a lower frequency (just like lower frequency sound travels further) and greater wall penetration. Actually, I have never had a router where the two frequency are the same strength, even right next to the router. It's not that it's weaker, it just doesn't go as far.

My concern is not really about range. I understand the differences between 2.4Ghz and 5Ghz. I am more curious about the two 5Ghz signals remitting from the 890L are showing an average of -10dBm to -15dBm differences in signal strength wherever I am in the house.

I have tried turning SC off and giving the two 5Ghz signals different SSIDs and all other settings are the same. And then I tried to transfer a file between my notebook and my desktop (which is hardwired to the 890L) and the throughput rate on the primary 5Ghz is noticeably slower. I am not the only one who noticed this, refer to http://forums.dlink.com/index.php?topic=65069.0 (Reply #9), that member also noticed the primary signal is a lot weaker.

As Furry has suggested I may give Dlink a call but they are only available 9am-7pm on weekdays and I am usually at work during those hours. I tried online chat, but its useless, the rep claims its normal to show a difference in signal strength.

[FurryNutz]

I checked my A1 with v1.10 in AP mode with SC disabled. Seen about a 5dbm difference between the 5Ghz radios. Nothing major. I'm in a downstairs location from the 890L thats upstairs and one wooden wall away. RSSI is fluctuation around -70-75dbm and Noise is -93dbm where i'm sitting with my 2008 Mac Book Pro.

There maybe a different in Revs and maybe a problem with your unit.

[bballstuffer]

Thanks. I have requested a replacement unit from Amazon. It's arriving tomorrow and I will provide my comments after.

[FurryNutz]

Hope the new units works better. 

[bballstuffer]

Got the replacement unit but its also showing the same behaviour so I think it just how the unit was designed.

[bballstuffer]

I found out the reason why my secondary 5Ghz gives out stronger signal than the primary.

I was reading Kong's guide on wireless setup for dd-wrt and in there it mentions that regulation limits allow higher power output on higher channels. Since the primary 5Ghz is restricted to channel 36-48 and the secondary 5Ghz is to 149-161, it makes sense the secondary 5Ghz is outputting a higher signal than the primary. Damn, I wish I have found this link earlier!

http://tips.desipro.de/2014/02/12/wireless-starters-guide-for-first-time-dd-wrt-users/

[FurryNutz]

Interesting, I didn't know that. I'll keep this in mind.
Some additional Info about 5Ghz and channels:
Dynamic Frequency Selection and
https://www.smallnetbuilder.com/basics/wireless-basics/33082-smallnetbuilder-s-wi-fi-dynamic-frequency-selection-dfs-faq

Added your linked info here as well:
Links>Wireless Installation Considerations

[Hard Harry]

I didn't think we were comparing 2 5Ghz SSID on one antenna, I thought we were comparing 2.4Ghz to 5Ghz. It makes sense that one would be stronger since they can't both use the same channels, the channels that are lower frequency are "stronger". Again though, I don't think one would actually have greater range, it's just the wireless adapter thinking it's stronger. I have never tested it though, so would be interesting to see the outcome. If two devices are connected to the different 5Ghz SSID, do they disconnect at the same time as taken out of range from the network?

[FurryNutz]

I think he was interested in the two 5Ghz wifi radios and each one of them seems to appear to have different signal strengths.