For full diagnostics, you ping AP, router, and some internet host.
That way you know where the real culprit lies.
In any case, some packet loss is acceptable for pure internet browsing. Using work related software packages, might need 0% packet loss for a user to work without loss of time (an app could be slow, freeze, need restart, or even miss data).
Either the AP to router is giving you problems, or the router to Google (or internet), though then probably all wired PC's would have the same problem.
Though 2 time outs in 40 minutes is very manageable. It's if there are more within minutes that _could_ give you a problem, as I said earlier, for just the casual browsing, it can be even higher without much problems.
As I said, it totally depends on what you need. Only clients to browse a bit, or a system critical database system that needs to be online all the time?
Seems you don't have problems on wired connections, meaning the servers probably will never have a problem. Sounds like you only need a bit of browsing, so in that case, yes it's acceptable.
For pinging inside a LAN, any ping timeout likely means 100% timeout, so something badly broken.