[FS#1192] 2.4Ghz wifi AP on mt7621 / Afoundry EW1200 doesn't work

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Alex Hewson (alexmbird) 

Attached to Project - LEDE Project
Summary - 2.4Ghz wifi AP on mt7621 / Afoundry EW1200 doesn't work
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - High
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Hi LEDE folks!

I'm running the latest snapshot (r5406-5e6792e) of LEDE on an Afoundry EW1200.  It's a vast improvement from the stock firmware - my heartfelt gratitude to the author(s) of the port.

There's one problem.  5Ghz wifi works fine but 2.4Ghz doesn't.  It detects my 2.4Ghz device and when I hit "scan" in LuCI it returns a list of nearby SSIDs.

But when I try to configure the device as an access point it isn't visible to any of my devices.  I've tried  various channels / settings but nothing makes a difference.

Steps to reproduce:

1. Install LEDE r5406-5e6792e snapshot (latest at the time of writing) on an Afoundry EW1200
2. Use opkg to install LuCI [NB: I don't think LuCI is to blame; it's just the interface I use]
3. In Network/Wireless hit "Scan" for "Generic MAC80211 802.11bgn" and verify it can detect other people's networks
4. Back in Network/Wireless, hit add (or edit) to configure an access point on that device.  Use any settings you like.
5. LuCI shows the AP as running but no other device can detect the SSID it's broadcasting.


More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1192