When a Global Cloud Service Goes Down, Does Your Office Stop Working?

When a global cloud service goes down, most offices do not stop completely, but they can slow down sharply if nobody has mapped which daily tasks need the cloud at that moment and which only need it eventually. Files marked for offline use, a cached mailbox, a local file server and a local AI tool keep people working; online-only files, browser-only apps and single-vendor AI do not.

This is a planning guide, not a report on any current event. It covers a simple dependency map, the offline settings Microsoft already provides, and local fallbacks such as the Synology DiskStation DS925+ NAS and the ASUS Ascent GX10 for local AI.

Which office tasks stop when the cloud stops?

Start with a dependency map: list the tasks people do every day, then ask what each one needs from the internet right now, not eventually.

Look for the rows where the offline column says "nothing". Those are where a change of settings, or a modest piece of local hardware, pays off first.

Will my OneDrive files open during an outage?

Only the ones already on your device. Microsoft's OneDrive Files On-Demand page states that online-only files cannot be opened when the device is not connected to the internet, while a locally available file opens anytime, even without internet access. Files you mark with "Always keep on this device" stay available offline.

The practical step: ask each team to mark the folders they would need during a bad afternoon (current projects, price lists, templates, contracts in progress) as "Always keep on this device". It costs disk space, so it suits laptops with enough SSD capacity; it does not suit whole department archives. The same thinking applies to an outage of your internet line rather than the cloud service, which our sibling post on internet outage and office network resilience covers from the network side.

Can Outlook still work if Microsoft 365 is down?

Partly. Microsoft explains that Cached Exchange Mode saves a copy of your mailbox on your computer and lets you work with mailbox items even when the network connection is slow or unavailable. It is on by default for Microsoft 365 and Exchange accounts, and by default 12 months of email are kept offline. So people can search old mail, read attachments and write replies; sending still waits for the service.

Two things to check: that staff actually use the Outlook desktop app rather than only the browser, and that the offline period suits roles that often look up older mail. Email will not help if the outage is email, so keep a phone list of key customers, suppliers and staff somewhere that does not depend on the same service.

Do Office desktop apps need the internet?

Not minute by minute. Microsoft's licensing documentation states that Microsoft 365 Apps remain fully functional as long as the computer can connect to the internet at least once every 30 days. After more than 30 days offline they enter reduced functionality mode, where users can only view and print documents. A short cloud outage does not affect editing local files in desktop Word, Excel or PowerPoint; browser-only users, however, lose editing entirely.

That is a reason to give office staff a licence that includes the desktop apps. Microsoft 365 Business Standard Annual Subscription (12 Months) is S$213.00 per user as listed on 24 Oct 2026; confirm the right plan for each role when requesting a quote. Licence tracking is covered in Your Company Has 20 Different IT Subscriptions.

Should important files also live on a local NAS?

For many SMEs, yes, as a second home for the files that matter most. A NAS in the office keeps working over the local network whatever happens to a cloud service, and doubles as a backup target. Synology describes Synology Drive as a private cloud for file management and sharing, with "Sync on demand" to pin a permanent local copy and the ability to restore earlier file versions.

The Synology DiskStation DS925+, S$1,260.00 as listed on 24 Oct 2026 and in stock, is a 4-bay NAS expandable to 9 bays; the Synology DiskStation DS425+ is S$853.20, also in stock (drives are bought separately). A NAS is not a substitute for backup discipline; see Your Expensive SSD Could Lose Data Without Warning and our ransomware prevention guide, and put the NAS and network kit on a UPS.

The cloud is a dependency like any other. Map it, keep a local copy of what matters, and know who decides when to switch to Plan B.

What happens to AI tools when the AI service is down?

Teams that have folded a cloud AI assistant into daily drafting, summarising or coding feel an AI outage straight away. AI providers publish status pages; OpenAI's, for example, lists its API, ChatGPT and Codex components and lets you subscribe to updates. Checking a status page tells you what is happening; it does not keep work moving.

A local fallback does. Tools such as Ollama, which describes itself as a way to run open models locally or in the cloud on macOS, Windows and Linux, let a team keep a capable model on its own hardware for drafting and summaries. For a team-wide service, the ASUS Ascent GX10 with NVIDIA GB10 and 128 GB of memory is S$7,200.00 as listed on 24 Oct 2026 and in stock; for a single desk, the ASUS Ascent QN10 AI Mini PC is S$2,375.00, also in stock. Local models differ from the largest cloud models, so test the tasks you rely on. Our opinion piece Are Businesses Becoming Too Dependent on ChatGPT? argues the case for multi-model plans, and when running AI locally beats the cloud covers the economics.

How do you know whether it is your office or the provider?

Check before you troubleshoot. Microsoft says admins can see service health under Health in the Microsoft 365 admin center; if you cannot sign in, Microsoft points to its service status page at status.cloud.microsoft and the @MSFT365Status account on X. Write these into the IT runbook with the name of the person who decides to switch to fallback mode and who tells staff. If the provider is fine and only your office is affected, the cause is more likely your internet line, firewall or a recent change; see why the next big software update could break your meeting room and operating system end of support for change and lifecycle planning.

Building a cloud outage plan with SourceIT in Singapore

SourceIT supplies Synology with local warranty, along with ASUS Ascent systems and Microsoft 365 subscriptions; confirm warranty terms for your SKU when requesting a quote. Prices are as listed on 24 Oct 2026. Browse Synology backup and data protection or the ASUS Ascent GX10 collection. For multi-seat licences and NAS bundles, see volume discounts and special pricing, use Request for Quotation on the product page, call (65) 6978 3502 or email Sales@sourceit.com.sg.

Frequently asked questions

Can I open OneDrive files without internet? Only files stored on the device. Microsoft says online-only files cannot be opened offline, while locally available files and those marked "Always keep on this device" can.

Does Outlook work offline? With Cached Exchange Mode, which is on by default for Microsoft 365 accounts, Outlook keeps a copy of your mailbox, 12 months by default, so you can read and draft mail. Sending waits for the connection.

How long can Microsoft 365 desktop apps run without internet? Microsoft says they stay fully functional if the computer connects at least once every 30 days; after that they enter reduced functionality mode, view and print only.

Where do I check whether Microsoft 365 is down? Service health in the Microsoft 365 admin center. If you cannot sign in, Microsoft points to status.cloud.microsoft and @MSFT365Status on X.

Is a NAS still useful if we use OneDrive? Yes, as a local copy of critical files and a backup target that works over the office network during a cloud or internet outage.

Can local AI replace a cloud AI service? For drafting and summaries it can be a workable fallback, but local open models differ from the largest cloud models. Test your key tasks first.