Official documentation checked October 14, 2026.
A “trouble connecting” message in Copilot is a symptom, not a diagnosis of a particular blocked domain. Service incidents, a proxy that interrupts streaming connections, an incomplete sign-in, or an app-specific problem can look similar. Ordinary websites loading successfully does not prove that all Microsoft 365 connections are working.
Use the following checks for work or school Copilot experiences in Microsoft 365. Keep the firewall and endpoint protection enabled. Do not delete document caches or uninstall Office product keys to investigate a connection error.
1. Identify the affected feature and check service health
Record the full message, the time with time zone, and where it appears: for example, Word’s Copilot pane, a Teams meeting feature, or Copilot Chat in a browser. Note whether sign-in fails before the pane opens or whether only a submitted prompt fails. Capture any request or correlation ID without publishing confidential prompt contents.
- One app or workbook: compare with another approved, nonsensitive file or the corresponding web experience, where available. This narrows the investigation; it does not prove that a local cache is corrupt.
- Several users at one location: ask IT whether the start time matches a network or security-policy change.
- Several locations or clients: ask the service desk to check for a matching Microsoft incident and account-level problems.
Administrators with service-health access can open Health > Service health in the Microsoft 365 admin center. Read the incident’s affected services, user impact, and updates, not just its title. An unrelated advisory does not explain every Copilot failure, and a matching advisory may have a supported workaround. Microsoft’s service-health instructions explain the detail view. If no matching issue is listed, continue troubleshooting rather than assuming there cannot be an emerging incident.
2. Test the required connections without switching off protection
On Windows, open Get Help, search for Copilot connectivity troubleshooter, and follow the diagnostics. Review any proposed change before accepting it, especially on a managed device. Save the results. This is Microsoft’s documented connectivity troubleshooter, separate from its license troubleshooter.
The network team should compare the affected route with the current Copilot network requirements and the endpoint lists linked there. Those requirements include the *.cloud.microsoft domain and secure WebSocket connections. Proxy timeouts or interfering TLS inspection can interrupt these connections even when a basic HTTPS page loads.
Microsoft does not provide a small, fixed set of individual hostnames that covers every Copilot scenario. Checking only copilot.microsoft.com is insufficient. Use the official Copilot connectivity test linked in the requirements, and have IT inspect blocked destinations, WebSocket handling, and proxy/security logs around the recorded failure time.
A network change should be made by its owner using the current Microsoft requirements and organizational controls. Do not create blanket exceptions for every Office executable, switch off antivirus, bypass a managed proxy, or remove a required VPN. If IT authorizes a comparison on another network, use a nonsensitive test and record both results; a difference identifies a route to investigate, not an automatic reason to disable its protection.
3. Separate sign-in and entitlement from Office activation
If the app asks you to authenticate, save your work and complete the normal sign-in flow with the intended work account. Reopen the app after a normal close. Report an immediate repeated challenge or an explicit error to the identity team instead of repeatedly signing out of every Microsoft application.
For an explicit access or licensing message, ask the administrator to check the feature you are using. Copilot Chat and the different in-app capabilities do not all have identical entitlements; a connection message alone is not a reason to purchase or reassign a license. Microsoft’s setup documentation also notes that newly assigned capabilities may take time to appear.
If Excel or Word separately reports that Microsoft 365 Apps itself is unlicensed, treat that as an activation issue with its own evidence. Microsoft states that ospp.vbs is not the licensing-management tool for subscription Microsoft 365 Apps; see its current activation diagnostics. Removing a product key is not a Copilot token refresh and can disrupt an installed Office product. Leave activation keys and licensing folders alone unless support has established a relevant activation fault and an approved recovery procedure.
4. Handle app-specific failures and protect unsynchronized work
If only one desktop app fails, record its version, save open files, and install the organization’s approved updates. In Office apps on Windows, user-controlled updates are normally under File > Account > Update Options > Update Now; see Microsoft’s update guide. A generic error is not proof that an outdated build caused it, so retest the same harmless action and record whether the result changed.
For Teams-only failures, specify whether the problem affects meeting Copilot, chat, or the Copilot app, and compare the supported web experience if your organization permits it. Do not look for an “Enable automatic proxies” switch as a standard Teams repair step or apply old Teams cache-folder instructions to a different client.
Do not empty OfficeFileCache as an authentication test. Microsoft’s document-cache explanation shows that the cache contains document content and can involve changes awaiting upload. A genuine synchronization fault needs a separate recovery process, with the latest work saved safely before any cache operation.
Send support the affected app/feature, version, failure time and IDs, scope across users/devices, any matching incident ID, and connectivity-test results. Redact account details from public screenshots. These facts let the application, identity, and network owners investigate the failing layer without trading away security or unsaved work.