Cloud-only point of sale is a reasonable design in a city with fibre to every unit. In a lot of the places our customers actually trade, it is a design that closes the restaurant for an hour on a Friday. This is not an edge case to be handled gracefully; for an overseas shop it is a base requirement, and it is worth checking carefully before you commit to any system.
Three modes, and what each needs
Single machine. One till, everything local. Needs no network of any kind.
LAN. Several devices — tills, floor tablets, kitchen screens — talking to a host machine over the shop’s own router. Needs the local network to be up. Does not need the internet.
Cloud. Several branches syncing to a central account, plus remote viewing. Needs the internet, and this is the only mode that does.
Most single restaurants run on LAN. The wifi router in the ceiling keeps working when the fibre outside is cut, so the floor tablets keep talking to the till, the kitchen screens keep receiving, and service continues. Nobody in the dining room notices anything happened.
What happens to the data
Transactions written while the line is down are held locally and synced automatically once connectivity returns. You do not run a recovery procedure or re-key a shift.
Within the shop, the host machine is the authority on pricing and stock. Two tills selling the last bottle of the same wine do not each decrement their own copy — deduction happens on the host, atomically, which is what stops the classic double-sell. That guarantee comes from the LAN architecture, not from the cloud.
QR ordering while offline
Guest QR ordering can point at the in-shop host rather than at a cloud service. In that mode guests keep scanning and ordering through an outage, because their phone is talking to a machine forty feet away over your own wifi. Cloud mode is what you switch to when you want one view across several branches — you can start on LAN and move up later without rebuilding the menu. See ordering by QR code.
Power is a separate problem
Worth separating, because people conflate them. A power cut and a network cut are different failures with different answers. Offline mode covers the network. For power you want a UPS on the till and the router — a cheap one that carries you fifteen minutes is usually enough to finish the tables you have and shut down cleanly. If your area has scheduled outages, plan for both; if it does not, you still need the offline capability, because the fibre outside does not care whether your lights are on.
What you lose while offline
Remote viewing from another country, cross-branch reporting, and any payment channel that itself needs the internet — a card terminal will not authorise without a line, and nothing in the software can change that. Cash, stored value and offline-capable tenders carry on. See end-of-day cash-up for how outage days reconcile.
