What it actually means
MTTR is a measured average. Add up the repair time on every fault over a given period, divide by the number of faults, and that is your mean time to repair. It sits next to two related metrics that often confuse people. MTTF, mean time to failure, is the average time a component runs before it breaks. MTBF, mean time between failures, is the average gap between one failure and the next. MTTR is the only one of the three that measures what happens after something has already gone wrong.
For a UK business buying connectivity, MTTR is the number that decides how a bad day plays out. An uptime SLA of 99.9% sounds reassuring on a quote, but it averages downtime across an entire year. The day the line drops, the only figure that matters is how quickly a human picks up, how quickly Openreach is dispatched, and how long until you are trading again.
In business
What this looks like at work
Picture a Saturday lunch service in a busy independent restaurant. The card machine stops talking to the bank at twelve forty. Two people put their cards back in their wallets and leave. The duty manager phones the provider and gets a hold queue. By the time anyone answers, the queue at the door has gone. That whole episode is your MTTR in real life. Now picture the same outage on a connection where the provider answers in under a minute, opens the Openreach case while you are still on the call, and tells you a clear next step. The fault is the same, the felt cost is completely different. This is why repair time, and the human behaviour around it, often matters more than the uptime percentage on a single day.