user16991: I would like to use my arduino even where there's no wifi router. I've only found people saying that it needs to connect to a router, but isn't the phone like a router when it's in tethering mode? Do I still need a mobile internet connection or can I do it directly?

user4143: A phone running in wifi tethering (mobile hotspot) mode is no different to a wifi access point or router. So yes, you can use that.
Chances are though that you will need a mobile internet connection in order to activate mobile hotspot mode in the first place.

16991: <p>I would like to use my arduino even where there's no wifi router. I've only found people saying that it needs to connect to a router, but isn't the phone like a router when it's in tethering mode? Do I still need a mobile internet connection or can I do it directly?</p>
 4143: <p>A phone running in wifi tethering (mobile hotspot) mode is no different to a wifi access point or router. So yes, you can use that.</p>

<p>Chances are though that you will need a mobile internet connection in order to activate mobile hotspot mode in the first place.</p>
