basic auth does not work on some government PCs

Our dev/staging sites are protected by Nginx basic auth to prevent search engine crawling. On some government-issued computers, the browser does not display the Basic Authentication login prompt. Instead, users are taken directly to a 401 Unauthorized error page, preventing them from authenticating.

The most likely cause is that the browser or system policy on these government-managed devices disables HTTP Basic Auth, since it sends credentials as unencrypted-looking Base64 and is considered weak.

We have several possible options:
1. Determine the scope of the issue. Does this affect all government-issued computers, or only certain ones? If it is limited to specific devices, ask affected users to use a computer that is known to work with Basic Authentication, such as a Mac, if available.
2. Allow trusted network traffic. If government-issued computers access the site from a known set of IP addresses, we could whitelist those IPs and bypass Basic Authentication for requests originating from them.
3. Replace Basic Authentication. Migrate to a different authentication mechanism that is compatible with government security policies.