Which WiFi standard do I need?

[DelJo63]

There's lots of hype and speculation on the advent of WiFi 6 so it's time to straight talk networking.

digitalcitizen.life has a nice summary of WiFi frequencies and technologies:

• Wi-Fi 802.11n is also referred to as Wi-Fi 4.
• 802.11n allows the use of two radio frequency bands,
• 2.4 GHz and 5 GHz, and can deliver data transfer speeds of up to 600 Mbps.
• 
  
• Wi-Fi 802.11ac is also known as Wi-Fi 5.
• The 802.11ac is the most common wireless standard today,
• as most routers sold during the last few years are
• 802.11ac-compatible. This standard, just like the 802.11n
• before it, supports MU-MIMO, but it can offer maximum
• data transfer speeds of up to 2.3 Gbps. The 802.11ac standard
• works only on the 5 GHz frequency band but most of the wireless
• routers that support it also offer support for the 802.11n
• standard on the 2.4 GHz frequency band
• 
  
• 802.11ax is also referred to as Wi-Fi 6.
• 802.11ax or IEEE802.11ax is a wireless networking standard that
• is still in the works and has not yet been approved.
• It is expected that it will be finalized and approved sometime during late 2019,
• This is the LOWER END of the two implementations proposed and will have the greatest range
• 
  
• 
  
• 802.11ad is a wireless networking standard that is also known as WiGig or 60 GHz Wi-Fi.
• However, because it works on a microwave range frequency (mmWave length), it has
• the significant disadvantage of not being able to pass through
• walls and has a range of only 3 to 32 feet (1 to 10 meters).
• It is "lightning fast," but it is designed to cover only one room
• when no walls or obstacles stand in the way.

Whereas, an approved 802.11ax has yet to be established -- AT LEAST await the approved standard before investing in new infrastructure equipment.