[RT-AC66U + Tomato Shibby 1.38] 5GHz Channel Width stuck at 20MHz

[Jacques Assert]

Q: Is this a good forum to post this question?

Was running various Merlin builds on multiple RT-AC66U. Attempting to get functional QoS, RMerlin suggested Tomato Shibby. Now, QoS is excellent but 5Ghz band stuck at 20MHz Channel Width and 288.5 Mbps Rate most of the time. There is a video that suggests a work-around, but it does not work on the three routers I've tried.

It appears possible to get 802.11ac working with 40MHz Channel Width and 600 Mbps Rate, but 80MHz is unreachable.

Q: Any suggestions for how to enable 80MHz Channel Width?

Note that Channel Width (80) and Rate (1300 Mbps) is displayed initially after Tomato install, but without clearing NVRAM there are a lot of other problems.

 

[Jacques Assert]

Originally set to EU, which limited Channel Width to 20MHz. Then to Canada/Australia/Sweden which were all given as suggestions in various threads. Australia/Canada enabled 40MHz. Eventually tried US, which allowed 80MHz. But the only difference between US and Canada is one 80MHz range, as indicated in the list below.

US offered 5 (five) 80MHz channels, while CANADA/AUSTRALIA offered 0 (zero) channels. It suggests to me that there is an error in the valid spectrum choice list for those countries.

https://en.wikipedia.org/wiki/List_of_WLAN_channels