Multisite subdomain not being recognized

Hello,
Thank you for reading this post! Here's a description of the issue we're facing.

CONTEXT
We have a multisite network running ~70 subdomain sites. The sites have all been running fine for the past year and a half. The primary site is mnknights.org, and each subsite is e.g. kc9139.mnknights.org.

THE PROBLEM
We recently switched the domain nameserver and SSL configuration (Let's Encrypt rate limits were causing issues as the network grew past 50 subsites). The switch went fine, and both the primary domain site, and the subsites, continued working - smooth launch! However, we have noticed today that about ~50% of the subsites are not working correctly.

e.g. kc4842.mnknights.org

There have been two different errors we've been getting:
1) This site can't be reached. kc4842's server IP address could not be found.
2) Siteground (hosting company) error "Oops! Website currently not available."

ATTEMPTED SOLUTIONS
For [1], we have double-checked the DNS domain settings, and are stumped. We do have correctly setup a wildcard A record *.mnknights.org that points to the correct hosting server IP address. However for some reason the browser/internet is not recognizing the wildcard A record? This record has not been changed recently.
Why is kc4842.mnknights.org not being recognized as an IP address?

For [2], we have double-checked the multisite settings, cleared the site caches, verified that the actual WP subsite files and database values are still in place (they are), and checked the wp-config and htaccess files (nothing unusual that we can find).

STUMPED
Does anyone have any ideas as to what could be going on? We're at wit's end trying to figure this out, and meanwhile half of our network is out :slight_frown:

Thank you for your help! Peace

  • Matthew

    Hi Ash,

    Thanks so much for your response! Yes I managed to fix it around 2:00am and was so exhausted, I fell asleep and forgot to update this thread. Sorry about that!

    For future readers, here's what the weird fix ended up being (I'm still not sure why this fixed it):

    BEGINNING STATE:
    - Hosted on SiteGround
    - WP Multisite subdomain network
    - The subdomains were all entered in as "Subdomains" in CPanel, pointing to the server public_html
    - Each subdomain had its own Let's Encrypt SSL certificate installed
    - All sites working correctly
    - Let's Encrypt rate limiting was causing SSL downtime issues, leading us to make the breaking change:

    THE BREAKING CHANGE:
    - We installed a SiteGround paid Wildcard SSL certificate for the primary domain (which would then encompass all the subdomains)
    - Since the wildcard SSL covered all subdomains, we removed all the individual Let's Encrypt certificates

    BROKEN STATE:
    - The subdomains were all entered in "Subdomains" in CPanel, pointing to the server public_html (no change)
    - A single SiteGround paid Wildcard SSL certificate was the only SSL installed
    - Waited 12+ hours to ensure everything was propogated correctly
    - Most of the subdomain sites were broken. The SSL loaded correctly with https://subdomain.primary.com, but the page served a blank SiteGround empty page error instead of the correct multisite from WordPress

    THE FIX
    - No idea why this worked, but:
    - Remove each subdomain from "Subdomains" in CPanel
    - Add each subdomain to "Parked Domains" in CPanel, pointing to the server public_html
    - Contact SiteGround support, they did some server magic ("We regenerated the vhosts of the NGINX service on the server for your account.") ("In other words we refreshed the information for the subdomains on your account on server level.")
    - The sites started working again!

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