Posted: Thu Oct 01, 2020 13:58 Post subject: [Solved] HT20 issue TP-link C7v2-AC1750
I recently bought a new router and decided to use my old TP-Link AC1750 as an additional access point to extend my home network's coverage. I walked through these steps on the wiki to reset the router and set it as an AP. I set up both wireless networks, but the 5GHz appears to only be broadcasting 20MHz channel width even when I have it set to 80 and it's much slower than it should be (20 Mbps right next to the AP).
I'm using the latest firmware (tplink_archer-c7-v2-US-r44467), but I've also tried reverting back to 2 different older firmwares (one from August and one from 2017) without any luck. I've also tried different channels and extensions and changing the Wireless Network mode to AC/N.
Any ideas for other things to try or things I might have missed?
Joined: 21 Jan 2017 Posts: 1782 Location: Illinois Moderator
Posted: Thu Oct 01, 2020 14:41 Post subject:
turn off allow channel overlapping...That is a setting meant for advanced users in Europe and regions that have funky 5ghz channel allocations. You shouldn't need to use that. It's also why you are being allowed to choose a bad setting. UL is not a valid setting on channel 44 without "overiding" it like you are.
The selection you made does not comply with normal 802.11 standards and so clients will not see/co-operate with your selection and it's why you aren't seeing VHT80.
Thanks for the info, especially on the channels and extensions. I've made those changes and rebooted the AP, but it's still using 20 MHz channel width.
Joined: 21 Jan 2017 Posts: 1782 Location: Illinois Moderator
Posted: Thu Oct 01, 2020 15:41 Post subject:
Looks like we have a bug in the code... 44 + 38 should be the channels being used but you can see that 44 + 42 are being used and so it's bunked....
use Channel 36 + UU or 48 + LL... the middle channels seems to have their code wrong and BS will likely throw a shit fit trying to "fix" it.... The extension channel center needs to be -6, not -2...
maybe keep the LU AND turn on channel overlapping...then see if it yields the right 44 + 38. If not, use the above suggestion.
I tend to stay away from the middle channels.
Tonight I will see if my R9000 yields the same results or if it's specific to your device. _________________ FORUM RULES
Thank you very much for your help! Hopefully your investigation yields some answers. I tested on the other settings you recommended with the same results. The screenshots are included.
I'm open to trying other channels also, but I'm trying to stay away from the upper channels as my other AP is using them (ch157 at 80 MHz).
Joined: 21 Jan 2017 Posts: 1782 Location: Illinois Moderator
Posted: Thu Oct 01, 2020 16:30 Post subject:
Yeah, as indicated, my suggestions (36+UU or 48+ll) are showing the right results and should yield the VHT80 you are seeking. Use those for now until we can tweak the code to yield the right selections when 40, 44, 153, and 157 are used.
BS's math is off in the code, I will start a PM with him and have a philosophical debate about it...off to find the SVN shit storm ticket where we thought we had this sorted...
what doesn't help all this is that BCM is opposite in their implementation of how this gets selected and BS doesn't have the appetite to re-write the channel selection code all over again....can't blame him either... _________________ FORUM RULES
Cool, let me know if you come up with anything. One thing to note is that even on the 36+UU and 48+LL channels, I'm still not seeing VHT80 in wifi analyzer.
Joined: 21 Jan 2017 Posts: 1782 Location: Illinois Moderator
Posted: Thu Oct 01, 2020 17:09 Post subject:
blowuptheking wrote:
Cool, let me know if you come up with anything. One thing to note is that even on the 36+UU and 48+LL channels, I'm still not seeing VHT80 in wifi analyzer.
Try to use another device or client...it could very well be the client you have is using a cheap 1x1:1 radio or doesn't have the support to see VHT80. _________________ FORUM RULES
My other AP is using VHT80 and I can connect/see it. Wifi analyzer is also seeing several other APs that are using VHT80 (see the earlier screenshots). For reference, the phone I'm using to connect and scan an an LG G7.