I know this is an old thread, but perhaps my experience will help anyone else in the same situation.
I used to have Comcast, which fed my wireless router, which had wired connections to my PC and Xbox, and wireless to my two laptops, tablet, and phone. I ditched Comcast because of issues I had with them, and wanted to use my phone as an internet connection, however I didn't want to tether all my devices to my phone as the range is much worse, plus I have equipment on my LAN such as NAS units and file sharing that I didn't want to give up.
There are two ways I could have went. I could do USB tethering from my phone to my wireless router, however the USB port on the router can't provide enough power to the phone to keep it charged. I also would have to run a long USB cord to get from the router to a spot where I get decent service, plus I can't easily use my phone as it's tethered to my router. I went the wireless route, which I'll explain below what I did.
- My phone runs as a normal mobile hotspot.
- I have an older wireless router (Asus RT-N16) running a third party firmware called Tomato.
- The RT-N16 is configured as a "client" and connects to my phones hotspot. Once it connects, all 4 LAN ports are usable for internet access.
- I have my RT-N16 router connected via ethernet to my Asus AC68U's (802.11ac wireless router) WAN port. So effectively the RT-N16 is providing internet to my AC68U.
- Now all my clients connect the same way as before. I have my two hard wired devices connected to my router, and all my existing clients are connected. I can still share files at 1Gbps over the LAN and up to 1300Mbps over the wireless.
So for a quick overview:
Android phone running as a mobile hotspot > Old wireless router acting as a client bridge > New wireless router > Clients