Yeah, it takes about five minutes max to get it set up, and then you can preview on mobile anytime you want..
Quick simplified version (assuming you have windows and ARE CURRENTLY CONNECTED TO THE SAME WIFI ON BOTH YOUR PC AND YOUR PHONE.
1) Go to Control Panel
2) Click System Security
3) Click Windows Firewall
4) On left side, now, click Advanced Settings
5) On the new popped up window, left side, click Inbound Rules
6) On right side, click New Rule.
7) Select PORT, click next
8) Select TCP
9) Click Specific Local Ports and Enter in " 50000-50100" (without quotes of course)
10) Click Next
11) Leave as "Allow Connection", Click Next
12) Select what networks recognize the rule. I leave all selected. It's not really an issue. Click Next.
13) The the rule whatever you want.
Now that that's done (only time you'll ever do it) All you have to do is go to C2, right click the icon, and make sure you "Run as Administrator".
After it opens, click on File. Near the bottom right will be a "Preferences" button. Click it.
Click on the "Preview" tab.
To the right of the "Preview on LAN Address" is a text box then a button with an ellipses -- "..."
Click that button [...]
Double click the only, or one of the, numbers that starts with 192.
Click OK.
Close C2 and open it again, remember to "Run as Administrator"...
Now click preview. Your browser should pop up your game and the address bar should have "192.168. blah blah blah"
Open your phone's internet browser and enter in these exact same numbers and click GO.
It may take a minute to load, but your game will pop up on your phone.
Any time in the future you want to preview on your phone, make sure your phone and pc are on the same wifi. Run C2 as administrator, go back to the preview preferences and re-select the 192 number. (This changes when you connect to a different wifi. I move around a lot and that's why I leave my firewall open and have to reselect the number everytime. Then restart C2 as admin and preview. You should not have to ever change the Firewall rule.