Changing Firefox’s secure-DNS setting can change where the browser asks for a website’s address. That matters when an organisation relies on its own naming or network policy. A page failing after the change does not automatically indicate a broken Wi-Fi adapter.

Record the setting and the affected name

Open Firefox Settings, Privacy and security, then the DNS over HTTPS section and its advanced options where shown. Note the selected protection level and provider before making another change. Record the exact work hostname and the error message, keeping internal addresses out of public posts.

Mozilla describes Default protection as adapting to conditions including VPNs, parental controls, enterprise policy and network signals. Increased or custom choices use the selected provider more persistently, while maximum protection can warn when a secure resolver cannot provide an address. These modes are not interchangeable troubleshooting switches.

Check the organisation’s intended route

Ask the administrator which resolver and VPN arrangement the work service requires. Compare the symptom with an ordinary public site and with another authorised browser. Preserve the original observations so a change that restores access can be understood rather than accepted blindly.

Use an administrator-approved setting or a specifically justified exception when required. Do not choose a public resolver to evade workplace filtering, and do not add a broad exception list because one internal name fails. After the agreed change, repeat the original work task and verify normal HTTPS behaviour.

DNS over HTTPS protects a DNS lookup connection. It is not a replacement for a VPN, website authentication or application permissions. If the name resolves but the page still fails to sign in, continue investigating that separate stage.

Source: Mozilla Support.