Subfolder network / multisite setup

I’m not entirely sure how to ask this without this being an incredibly vague general question! We are running local environments on Laravel Valet, using Bedrock to run WordPress. We are attempting to set up a network / multisite, using the subfolder / subdirectory setup and are coming across stumbling blocks.

We have set up the primary site and have installed and activated this version of the Multisite URL Fixer plugin - GitHub - owlsdepartment/multisite-url-fixer: Fixes WordPress issues with home and site URL on multisite when using Bedrock. We have not yet changed any Nginx configuration for the site.

The primary site admin and frontend are both working with no problems. We have successfully created the first “child” site on /site1. When trying to access this site’s admin, the linked-to URL is /site1/wp-admin. Changing the siteurl to /site1/wp in the database fixes this, but the admin is inaccessible and instead we see the front-end of the child site with a broken admin toolbar.

We understand this is probably a routing problem, but does anyone have an optimum setup for Bedrock network using subfolder setup?

Thank you!

We used to use valet too and think we found the answer here…