[Dylan16807]

What exactly are you saying is wrong?

If you have to replace the router, there's a 10% chance that new router is broken. But you only replace when the first router is broken, so it's 10% of 10%.

Read it as "a strategy of replacing when needed" rather than "replacing in all cases for the hell of it".

[Mysterix]

The strategy "Buy 2 routers, and if the first one fails, then use the 2nd one" is ok, and gives you the 1% result.

My (little) problem is the sentence "Replacing your router (or firmware) almost always fixes your problem.", because if the first router is broken, replacing it will only fix your problem in 10% of the cases, which is not "almost always".

[Dylan16807]

You don't actually have to buy a second router upfront, so that's not a good way to word it either.

I'm struggling to find a great way to put it. Maybe "a one-replacement backup plan gives you a 99% chance of success"? Close but not very elegant.

"Replacing your router (or firmware) fixes the problem except for 1% of all router buyers"?