Creating index on Prestashop

We have a new prestashop in which we have imported about 7000 products. We don't succeed to create the indexes for these products. We are getting a gateway timeout. In the parallel plesk panel we already tried to install the corn job. In the PHP setting we have a timeout of 600. We only want the reference, description, category and manufacturer indexed. But we don't succeed. We need this index today. It looks as there are about 500 products indexed in a run. The option ' Add missing products to the index ' isn't working as expected. After executing this, the