Anyone explain how/why iPhone wifi?

May 28, 2016
So here's the pickle. (And first post) TWC router with built-in wifi right. Come home every night, fire up PS4 (connected via CAT 5), nothing else is on my router wirelessly at this point ( have a Tablet but it has been off for months and was put in airplane mode before I turned it off), router is mounted to the wall. I can see the slow steady blink of the lan from the PS4. However, I notice the rapid wifi light going off too? iPhone wifi is still off at this point and it's only able to use 3G but here's the kicker I'm asking about. Wifi flashy connectivity indicator stops when I power the iPhone off. Any thoughts? Guess's? Ect. Again, I have used/still use a few net monitor apps(not the free versions either); Net analyzer, system monitor pro, and fling. My network is password blocked and unique for both login and pass so I seriously doubt it's a neighbor (I disabled the guest option when I first got the router). I have performed the "iPhone power down -> wifi stops" multiple times and I get the same results. The silly reason I ask all this is because I want to know if it's the phone using the wifi without permission (anyone else's do this?) or (doubt it) if somebody is getting free wireless internet and if so, they are waaaaaay smarter then I at network security.
P.S. The other aspect of this is that IF the iPhone can access wifi without permission, your contacts, passwords, PII, is accessible regardless of you turning the wifi "come on in and spend some time lookin around" vacancy sign to NO! Can lock down my home network, use crazy multi-upper, lower, number, special character passwords on everything I access the wan with, but what good is that if my phone is actively accessing wifi without my knowledge? Not much really. Suppose I could just give up having a smart phone and get a old school "calls only" type.
That is weird. Who knows with apple products though. They may be doing something weird and undocumented.
When you say wifi is off do you mean turned off or simply not connected? When it not off it is still polling.
A wifi light blinking means nothing, even with no devices connected, it may still poll for devices or "blink" My router does the same thing and our iphones are only on it sometimes, but even with wifi off, routers wifi activity still blinks.

And yes my wifi is password protected and I have no guest network (I never have guests anyways. eff people)