Ok, so this actually turned out not to be a WordPress or Multisite issue after all. It turned out that it was actually a problem with the Let’s Encrypt SSL certificate that was causing the issue. Re-issuing the Let’s Encrypt SSL fixed this for me.
Ok, so this actually turned out not to be a WordPress or Multisite issue after all. It turned out that it was actually a problem with the Let’s Encrypt SSL certificate that was causing the issue. Re-issuing the Let’s Encrypt SSL fixed this for me.