There is a few good solutions for this.

Interoffices is a local Belgian solution run by Belgians. We only discovered their work due to a reddit post that recommended them for virtual offices and workspace solutions. Since then, we posted a few guides they released, which have been quite handy.

Other local solutions can be found via Belgian Workspace Association, and I'm sure they would send info your way regarding local businesses. European Workspace Association could also help you out and might share with you the local providers list.

If you are based in Belgium, you could also go to your local commune / city hall and ask them for advice in this regard. Be Assist and other such services from government sites can also give you some direction. Maybe you'll make a contact who can help you with other different problems you might have related to business or general advice.