Each country in the world controls their own wireless spectrum with most following the same frequency standard.
Some countries however add something’s other countries don’t. When this happens manufactures that sell wireless devices like routers build firmware /software that can be changed from one country to the next.
Channel 14 is one of those things that fall into this category.
Original channel 14 could be used in United States but was later banned and removed from routers.
Channel 14 is on the highest end of the WiFi frequency and works in the 2.484 GHz spectrum. It is designed to only work with 802.11b legacy routers.
If the country code is changed in the router to Japan then channel 14 can still be used since it is legal in Japan.
In America channel 14 was banned in 2005 and has it marked as restricted and the FCC uses language such as “No operation on channel 14 is allowed”.
It is a bit of a mystery why they banned this channel working at 2.48 GHz is a well known frequency that microwave ovens use when they are turned on. Possibly this frequency interferes with surveillance equipment the government and states have began to use widely, such as traffic cameras.
It is still a mystery since a home wireless router doesn’t transmit that far. Usually max transmitting power of a router is 300 feet with the rare exception of someone using a wireless booster possibly a 1000 feet.
The consequences of using channel 14 is not specified although technically disobeying the FCC is a felony. Although I highly doubt they would come knocking on any ones door for using it unless they had a huge transmitting output.
The reason channel 14 is interesting.
In a crowded WiFi environment packet collisions happen when two routers are on the same channels and transmitting. When packet collisions happen the router must resend the packet slowing down the whole network.
The 5 GHz range has been introduced with Dual Band routers to fight the overcrowded 2.4 GHz band but a signal on 5 GHz doesn’t travel as far as 2.4 GHz can.
For this reason manually setting a router to a channel that is unused on the 2.4 GHz range in a crowded area can greatly boost a signal and transmitting speed. It should be noted that there is overhang on channels so for example if channel 5 is used some data will be transmitted on channel 4 and 6.
Since channel 14 is no longer used even in crowded places a router setup on channel 14 should theoretically outperform all the others fighting to get a signal through.