Switch SolrServerConfig from embedded to standalone

We are using hybris 5.5

What is the proposed way to switch from embedded to standalone solr server? It is not possible to change the SolrServerConfig using impex or hmc, because the attribute mode is not editable.

I get the following message by executing the impex:

 attribute de.hybris.platform.solrfacetsearch.jalo.config.SolrServerConfig.mode cannot be changed except during item creation

Regards

Wolfgang