Indexing is a task that should always be run from the server side, instead of running it in your browser or via HTTP/HTTPS with wget or similar.
If indexing runs directly on the server it spends the least possible amount of resources, and is not vulnerable to being interrupted by web server time limits.
Also, on the command line Servebolt allows for a higher php memory limit, which may be required for larger catalogs to finish indexing successfully.
Log in to SSH and run the indexer like this:
wp algolia reindex --all
If you run WordPress in a Multi-site network, you also need to add a URL parameter.
wp algolia reindex --all --url=mydomain.com
After this successfully completes, you can set up a cron job in the admin panel to run this once nightly.