Posted: Fri Jan 27, 2023 4:41 Post subject: PROBLEM - Routing differnces 2.4Ghz and 5Ghz wlans
I have Linksys WRT1900ACSv2 running r51306 (01/15/23).
Generally no problems - seems to be very fast even with 20+ devices actively using.
I run both the 2.4 Hhz and the 5 Ghz wlans, and also have 4 devices connected by Ethernet cable. It is plain simple, single layer home network 192.168.9.1 (router), and all devices in same subnet.
Brother printer connects to 2.4Ghz. It is not capable to connect to 5Ghz. Address is: 192.168.9.228.
Some early problems (now fixed) with Apple AirPrint. Printer was not broadcasting its existence. That was FIXED by enabling ipV6 on the Printer (via printer's web interface). Then iOS and iMac users can detect the printer as AirPrint device, and can print. Windows & Linux users never had problems, for them no difference if ipv6 is enabled or disabled. They do not use AirPrint, they just use the address: 192.168.9.228 to access the printer.
THE PROBLEM -
if a device joins the 2.4Ghz wlan, it CANNOT see Printer. It CANNOT PING 192.168.9.228. And obviously, if is Apple device, NO AirPrint devices are detected.
If same device joins 5Ghz wlan, it CAN see the Printer. It CAN PING 192.168.9.228. And also, if it is an Apple device, IT DOES detect the printer as an AirPrint device.
Example: my windows 10 laptop, join 5GHz can ping 192.168.9.228. Join 2.4Ghz, then cannot ping 192.168.9.228.
TROUBLESHOOTING:
Hmmm... Maybe if join 2.4 wlan cannot ping anything ? No, I tested that. I can join the 2.4 wlan and ping all the other (pingable) devices, just not the printer at address 228. BUT MAYBE THE PRINTER IS THE ONLY DEVICE using ipv6 ? I do not know much about ipv6.
So I looked at the obvious thing: In ddrwrt Wireless tab are there any differences (2.4 v 5) ?? Answer: Seems all the same (Even looking in Advanced Settings).
To me (probably wrong) it seems like a ROUTING problem. If join on the 2.4 you cannot ping it. But if join on the 5Ghz can ping it. The printer itself joins on the 2.4 - which makes it even more weird.
If laptop connects by Ethernet (not wifi), it CAN ping printer and CAN print to it.
Joined: 18 Mar 2014 Posts: 12887 Location: Netherlands
Posted: Fri Jan 27, 2023 11:04 Post subject:
I am not a WLAN expert others like @ho1Aetoo or @MSOengineer know a lot more.
But I see a lot of settings which can be improved.
Your main problem you described is that you have AP isolation enabled. disable it and clients should be able to see each other.
But using dynamic width, auto channel, Radar detection, Network mode are all different than I would
use.
Actually amazing you did not encounter more problems.
I thought, obviously wrongly, that AP isolation meant that it isolated to only see other devices WITHIN their wlan. Meaning 2.4 wlan devices should be able to see ONLY other 2.4 wlan devices, but could not see devices on any other wlan.... You are saying that OPPOSITE IS TRUE, that AP isolation PREVENTS seeing any other devices on the SAME wlan - but allows seeing devices on other wlan.
Sounds like that will fix my problem ! Thanks
Followup question, how (if even possible) to limit devices to only see other devices on their same wlan, and NOT be able to see devices on the other wlan ?
Hi @egc and thanks for replying. Thanks also to @ho1Aetoo !
Quote:
But using dynamic width, auto channel, Radar detection, Network mode are all different than I would use. Actually amazing you did not encounter more problems.
I had read that link fully, and adjusted all those settings multiple times. I am OPEN to change any based on recommendations here.
I moved a few weeks ago from a non dd-wrt router to this setup. The starting point was plain, plain plain defaults for everything "auto", 20Mhz wide, "auto"... etc BUT... all users (including my own laptop) screamed at me about the slow wifi since the router change.
The main thing that changed the wifi connection speed for my own laptop (I only use 5ghz wlan) seemed to be "Wide HT40 40Mhz". With that (alone) I connect to the wifi at 400Mpbs. Other users also stopped complaining about it after that change. Maybe the 400Mpbs connection is being caused by somethings else - but thats how the 5ghz settings got to their current configuration.
About the 2.4Ghz wlan - all the complaints - have been about "cannot print". Nobody on the 2.4Ghz complained about speed or reliability.....
BUT -- if any specific changes that you would recommend ?? I would be VERY happy to try them out
Which setting is "radar detection" I do not see that one ?
For 5Ghz WLAN AC you best use 80Mhz channel width
So normally if the spectrum is clean the 80Mhz setting offers the best bandwidth especially since this is also a setting that is supported by all AC clients (unlike 80+80Mhz and 160Mhz).
It is usually also advantageous to select the channel manually.
Auto-Channel selects any channel where there is little noise but does not take into account the capabilities of your clients. (not all clients support all channels)
Which channel you should choose exactly I can't tell you now.
It depends on several factors like the regulatory domain and your neighborhood.
Under the following link you can find a list of valid channel settings:
There are only 6 possible 80Mhz blocks, so you can limit yourself to the following channels for testing purposes
36+UU
52+UU
100+UU
116+UU
132+UU
149+UU
the other combinations differ in the localization of the 20 and 40Mhz channel within the 80Mhz block.
So it only matters for 20 and 40Mhz clients - the 80Mhz performance is the same within a block.
The following should be noted:
36+UU
52+UU DFS
100+UU DFS
116+UU DFS RADAR Detection
132+UU DFS
149+UU in Europe for low range
Clients are only allowed to scan passively on DFS channels, which means they have to wait for an announcement from the router, so it may take a little longer for clients to find routers on these channels.
The block in the middle is the radar block often used by Terminal Doppler Weather Radar (TDWR).
Radar systems are so-called primary users and when the frequencies of radar systems are used, WLAN users must clear the frequency and switch to another channel.
The above channels are e.g. in Europe only released for low range - so they have the lowest transmitting power.
In the linked Wiki topic there is also much to read.
Whereby some statements are not true.
the passive scan on DFS channels cannot be switched on or off by "radar detection".
because this is done by the client and not by the router, the clients all have their own power and regulatory tables which forbid the client to actively scan on these channels - no router setting in the world would change this.
regarding the isolation of WLAN interfaces, it is easiest to work with unbridged VAPs
and there are in the forum everywhere distributed instructions from egc
I have these settings on wrt1900acs v2 and everything is fine _________________ Internet provider https://en.wikipedia.org/wiki/RCS_%26_RDS 1Gbps
WDR3600 rev.1.5 - DD-Wrt
Linksys WRT1900ACS v.2 DD-Wrt/-OpenWrt
For 5Ghz WLAN AC you best use 80Mhz channel width
So normally if the spectrum is clean the 80Mhz setting offers the best bandwidth especially since this is also a setting that is supported by all AC clients (unlike 80+80Mhz and 160Mhz).
THANKS @ho1Aetoo
I am reviewing every line of your POST and I will make the changes accordingly. Thank you !
@ho1Aetoo I would also like an opinion for wrt1900acs v2, country Romania, 5Ghz, VHT 80Mhz channel 36 and 2.4Ghz, channel 1, VHT 40Mhz are the correct settings?
romania is an EU member state and all EU member states have the same regulatory requirements.
and there is no such thing as the correct setting, it also depends on your neighborhood and your personal preferences.
If the passive scan stuff doesn't bother you, then there's nothing stopping you from using the other channels. (except maybe the upper frequency block as this has as said only 13dB)