Hard Wired AP or router as AP-Use the same channels or different ones?

[punit]

Quite a long time ago I was taught that when trying to extend your wireless coverage, the best plan was to use the same SSID's, PW's, encryption settings on both but always use different channels on each band, with 1,6, or 11 being the preferred 2.4GHz channels because they are the only non-overlapping ones. I was also told that if you leave both on the same channel they will actually see each other as "interference" and this will negatively impact throughput.
I was recently challenged on this and was argued that this is incorrect and that the AP and primary router should both be using exactly the same channels.
I looked at several youtube videos on configuring a 2nd router as an AP and interestingly none of the half dozen or so I looked at even mentioned the channel settings at all.
Is there a consensus on this issue? Have I been wrong all these years?
Also in the same discussion, it was argued that setting fixed bandwidth 20 or 40 on the 2.4GHz band and 40 on the 5GHz band. I was under the impression that since many manufacturers have adopted the "good neighbor" policy that leaving the bandwidth set to "auto" was best so when local conditions allowed, devices could connect with the optimum bandwidth and speed? Is this information correct or is there a better consensus?

[YeOldeStonecat]

Multiple APs on the same network....Same SSID, Same security settings, and neighboring APs should be on non overlapping channels. Correct.
In theory, "auto" should work, but in the real world.."auto" channel does not work well. Depends on brand, firmware version, etc...even then, I usually prefer to manually set the APs staggered on 1,6,11..even n large commercial setups with 20x or more APs on the same network.

[Philip]

As already suggested, neigboring APs and WiFi routers should be on non-overlapping channels. I don't always use 1-6-11, as long as you do a site survey and you are 3 channels away from any strong signals you are good.

As to the 20 vs. 40MHz channels, it is too vendor-specific, both clients and APs. In general, channel bonding (40MHz instead of 20MHz) works well with strong signals when you are close to the AP, however it is worse than regular 20MHz channels at longer distances with weaker signals. There is a bit more info here: http://www.speedguide.net/articles/wire ... weaks-5681