Problems with WordPress multisite directories/url structures and admin access after migration

I’m trying to migrate a multisite WP installation to a new server. The network consists of a simple parent site that redirects users to one of four subsites based on their location. E.g. if a user from the UK visits the site, they’re redirected to the subsite.

Before the migration, each subsite’s theme & plugin resources (images, css, js etc.) were available from the subsite’s url, e.g. After migrating the site to the new server, the resources are no longer available from the subsite domains, but are available from the parent site’s domain, e.g. This is causing all the stylesheets, images & js for each subsite to 404.

The other issue is that, although the main multisite network admin is accessible (, the subsite’s admin panels aren’t accessible, and going to, for example, produces an ERR_TOO_MANY_REDIRECTS error.

I feel like the two issues might be linked somehow but I’m not sure. Does anyone know why this might be happening and how I might be able to fix it?