Default [Q] Modem/Baseband problem on N5100

Hello, I recently flashed my Note 8 N5100 from official CM 11 to custom ROM SlimKat beta 2.4
I have internet connection problem using 3G, sometimes it doesn't connect and sometimes it connects to internet randomly
In my previous ROM, CM11, I don't have that issue
My S4 doesn't have that issue either with same SIM card.

I have previous experience in my S4 where you must flash a particular modem before flashing to newer ROM (OMEGA ROM) to make 3G connection works, so I think it's modem/baseband problem.
In Settings -> About Tablet, my Note 8 Baseband version is N5100XXCMJ2

Is it because of my recently flashed SlimKat or modem problem?