If you wish to improve the outdoor coverage, in your garden or on the terrace of your restaurant by means of a Wi-Fi router outside, you need to know that only the 2400-2483,5 MHz and 5470-5725 MHz frequency bands are allowed.
The other bands may only be used for indoor installations.
Installing a Wi-Fi repeater is not an ideal solution.
In practice, an older repeater model will halve the maximum speed of your Internet connection.
Apart from that a Wi-Fi repeater should always be placed at a location where the signal is still good.