This is a setup that I use in hotels to stream to chromecast bridged from hotel wireless OR to cast my screen without hotel wireless. Also, I use my Anker E3 portable battery, http://www.amazon.com/gp/product/B009USAJCC/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 to connect to the chromecast since hotel outlets are hard to reach or TVs don't have a USB.
Here's what works for me....(This is how I set everything up before I went on the road).
1. Get a Hootoo travel router. http://www.amazon.com/gp/product/B00HZWOQZ6/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
2. Download hootoo trip mate. https://play.google.com/store/apps/details?id=hootoo.wd.activities
A. Move the button on the outside of the hootoo to wireless.
B. Setup the router on "YOUR" home network via the app. The app will guide you to name a new WiFi network created by the hootoo router.
3. Setup your chromecast using your hootoo created WiFi network, NOT your main home network.
A. (The hootoo router will be connected to your home network while creating it's own WiFi in which chromecast will be connected)
B. At this point your chromecast is configured to recognize and work on your hootoo WiFi only.
4. If you want to watch a chromecast that DOES require Internet (podcast, Netflix, etc.) Goto the hootoo trip mate app and select a wireless network to attach to. The hootoo app then configures the router to bridge the network into your new hootoo network you created for your chromecast.
5. If you DO NOT need Internet connectivity and just want to cast your screen; make sure your hootoo router is on. Select the hootoo created network on your phone or tablet or laptop. Then via your chromechromecast app, select your chromecast device. You should now see the TV Chromecast screen say that Internet connection lost. NEVER MIND THIS and goto cast screen within the chromecast app and since you are connected to a WiFi network, your tablet, laptop, phone screen WILL mirror on the TV.
6. This took about 10 minutes to set up everything out of the boxes... I've tested this several times with my home airport router disconnected.
7. The hootoo router also has a USB port for thumb/hard drive. This streams to anyone on the network, simultaneously.
8. So now, when I get to a hotel, I plug in micro usb power to the router and open app on phone or tablet. Next, plug in Chromecast and change tv input. That's it. Since everything was configured at home, it's literally plug and play...