[FS#627] rt2x00: mt7620 channel regression

[LEDE Bugs]

The following task has a new comment added:

FS#627 - rt2x00: mt7620 channel regression
User who did this - Christian d'Heureuse (chdh)

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I had a similar effect with two Netgear EX3700 (MT7620A).

When the channel width was 20 MHz (the default), the 2.4G WLAN did not come up after a cold boot. In the logs and status info everything looked normal, but the network could not be seen from other devices. The 5G WLAN worked fine.

The command "iwinfo wlan1 scan" showed the message "scanning not possible", but after that, the 2.4G WLAN came up and worked normally. Even after a warm boot ("reboot" command) the 2.4G WLAN came up again.

Since I changed the channel with to 40 MHz, the problem is gone.
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=627#comment2220