By default, wireless devices use 20MHz channel. To improve the speed, HT40 broadens the bandwidth by binding two continuous 20MHz channels or discontinuous 20MHz channels. HT80 binds four 20MHz channels to get a higher speed than HT40. 802.11n and 802.11ac both can supply 20MHz and 40MHz channels to be used in WLAN. The upper limit for this parameter varies, depending on the 20/40 MHz mode for a 5 GHz frequency band radio: 20MHz mode: 58km ; 40MHz mode: 27km; Note that if you configure a value above the supported maximum, the maximum supported value will be used instead. Values below 600m will use default settings. Range: 0-57km (40MHz mode), 0-27km (20MHz But I've seen some products that seem to have a 20MHz-only mode, a 20/40MHz mode, and a 40MHz-only mode. If you have equipment like that, and you've put it into 40MHz-only mode, then it can only transmit when the whole 40MHz-wide swath of bandwidth is free, and it can be interfered with by anything in the whole 40MHz wide channel. 2.4 Ghz WiFi: 20 MHz vs 40 MHz vs 80 MHz. If you're using 2.4 GHz, the answer is simple. The best bandwidth for 2.4 Ghz is 20 MHz. In the majority of cases, using wide widths on 2.4 GHz isn't worthwhile. The performance tradeoffs from interference on overlapping channels will likely outweigh the throughput benefits. .

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