What is proving very useful in many retail shops now is mesh WIFI. What is happening is that it is excellent to rig a computer and use it around the shop. Some uses are free cash registers and stock control units where it is convenient to be able to move the computer to the point where it is needed.
The problem can be that often people have dead spots or areas of horrible reception. You can get an app on your smartphone to identify these spots.
What you do is move around the shop with the app going seeing where there are spots with lousy coverage and then try is to avoid those areas with WIFI. If its an area that you have to have what you can try to do is try to move your internet WIFI router around so that it can reach those areas, but often this has limited success. Plus in a shop, it can be an eyesore. What we did in one shop is put the WIFI router high up on the ceiling with the security camera. Looks great there but the problem here is if someone has to change a setting on the router, it is now impossible.
The most popular way today to extend the WIFI around the shop is to use now mesh WIFI. You get boxes like this.
These you place around the shop to improve the WIFI signal, so you tend to get better speeds as well as less dead zones. Plus you get a more extended range. One client of mine now can use his WIFI in the coffee shop over 100 metres away.
The other big plus is that most of the good ones also give you better management of your WIFI, e.g. you can set someone up with WIFI for a limited time, e.g. 2 hours and then it automatically cuts off their WIFI. You can also restrict people from accessing sensitive equipment.
If any of this interests you, please let us know.