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When attempting to bring up our website internally it says that our lets encrypt certificate is expired. If we try to access the web site externally it comes up just fine with a certificate from Cloudflare
It looks like you are using the Cloudflare CDN. In this case there are two HTTPS connections and each has its own cert.
The HTTPS connection between a client (like a browser) and the Cloudflare CDN Edge uses a cert the Edge obtained and manages.
The HTTPS connection between the Edge and your Origin Server has a cert on your Server that you got.
You can see your cert history with a tool like crt.sh (see here).
The reason you see the LE cert when checking locally is you are connecting to your Server directly (I presume).
So, all looks fine to me. Except, you should review your origin server to see why the cert is not renewing. You must have your Cloudflare settings set to ignore expired certs and that's why normal browser connections still work.