Which NC5 hotspot mod did you try installing? As far as I'm aware, there's no "mod" which work for stock NC5. You can try a custom NC5-based ROM which includes wifi tethering. These have worked for me with no issues.
If you're running the stock NC5, one thing you can try is getting your MSL and adding "dun" to your apns. The process is outlined
in this thread.
You need to read the forum, all the questions are already answered you just need to search and look not just ask.
Step by Step:
Get your MSL/SPC number using the app from this link:
http://tools.flashingtools.com/SPCUtility.apk
Dial ##data#
Select Edit
Put your MSL # and click OK
Scroll to bottom and select More
Scroll to bottom and select LTE APN Settings
Got to APN2 LTE internet
Go to APN type
Add ,dun at the end
Now it should be default,mms,dun
Got to APN2 EHRPD internet
Go to APN type
Add ,dun at the end
Now it should be default,mms,dun
Go to Settings
Change Hotspot to ON
Done. It should work now.
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