Due to DHCP, Managed Solr users sometimes find that their computer’s IP address has changed, invalidating their IP Filter access to Solr. Many people then create a new IP Filter without deleting the old one. The list of IP Filters grows monotonically.
At some point, users find that they cannot add one more IP Filter to the existing list. They can go through the motions, but the new filter does not persist.
Cloud servers have a maximum number of IP rules permitted, which varies from once Cloud Provider to another. The deployment also has some “internal” filter rules that the user cannot view. Therefore, the number of IP Filters you can define in Managed Solr varies from one deployment to another. The limit is usually in the mid-40s.
If you think you are in this situation, delete a filter from the list and try again. If you can then add a new filter, you have identified the problem. Unfortunately, SearchStax cannot raise this limit. The only solution is to weed out the obsolete filters.
Note that you can adjust the “prefix number” of the IP Filter to grant access to a subnet instead of an individual computer. That might help you free up some space on the list.