Are there any places to leave luggage in Brussels, for short and/or long periods of time?

Please note, as of 26/10/2018, all of the lockers at Brussels Central station are not working. We used a company called Nannybag. We paid online and the drop off was a tourist gift shop opposite the station on Rue Duquesnoy. It was 6 Euro per bag.

The lockers at the airport are at level 0; you have to go outside and to the left (follow signs of lockers). I was able to stack 2 big bags and a carry on with additional laptop bag. You need to add only 1 Euro to lock (red light) and then pay when you come back. The lock is electronic and one cannot add lock of their own. The coin dispenser machine does not work and so make sure when you come back you have enough coins. The free interphone does work and you can get someone on other side. I used it for 72 hours. When you come back, scan the receipt and the display will show you the amount to be paid. Once you add required coins, the locker opens up (green light).

On Brussels- Midi I saw two deferent lockers: staffed and self service. I used the self service for two cabin size suitcases and a backpack - all fit in the middle size locker, costed me 5 €.

Near the Centraal station, I used a service called Eelway (https://www.eelway.com/en/luggage-storage/brussels). I left my luggage there for 3 days while I was in Ghent. I think they have other locations in Brussels as they work with local shops where you can store your bags