I have been experimenting (ar750s / 3.100 / default US region) with different 5ghz channels and have noticed some issues:
When the primary channel is higher, then the noise level reported in luci overview or luci wireless often fluctuates to 0dbm:
1: select channel 161 with width of 80mhz. Every few seconds, luci reports 0dbm signal.
2. select channel 48 with 40mhz width. Every few seconds, luci reports 0dbm signal - not 100% reproducible though.
On top of this, channel 165 also has this effect whether it is primary or secondary channel as shown when using it with only 20mhz channel width.
OTOH:
- select channel 157 at 40mhz (bonds with 161) - there is no weird 0dbm issue.
- seledt channel 44 at 40 mhz (bonds with 48) - there is no issue.
So two things to take away:
- If the channel bonding is negative (ie. the main channel is higher than the secondary channels) there tends to be a 0dbm issue - it is most common with the higher channels.
- If the channel 165 is used as primary or secondary channel, there is the 0dbm issue. This is 100% reproducible for me.
Is this 0dbm issue tangible? It’s hard to tell whether this is actually causing any issues as the router seems to function ok despite it.