I recently upgraded a 9HPn router from 6.18 to 6.33.3 and now I cannot use either “20/40MHz Ce” or “20/40MHz eC”. When I try to use either of those two channel width options, I see an error at the bottom of the Interface dialog box (in WinBox) that says “no supported channel”. This problem does not exist in 6.18. Also, unlike 6.18, there are no options to choose from in the Frequency drop down list other than auto.

I have also noticed that if I set the channel width to say 10MHz and then set the channel to 907 (lowest 10MHz channel) and apply changes and then go back and change the channel width to "20/40MHz Ce", even though the Frequency option automatically gets set to auto, the status tab of WinBox wireless Interface dialog box still shows 907 as the current channel and 10MHz as the current channel width.

Any idea on why this is happening and how I can resolve this issue?