camera disconnects when 3G dialed from 3G router

i have neo cam NIP 03 clone (i think so, mine has h.264 decoder also).

my network is like this camera :-

3G USB > TL MR-3020 wifi router > IP cam (wifi)

and for PC :-

3G USB > TL MR-3020 wifi router > PC (LAN cable)

without 3G connection (i.e. internet) , i can access my cam on PC (i.e. on LAN)

but when i connect USB router (TP LINK _ MR3020) to my router and

connect router to internet , camera instantly drops connectivity with

wifi router. so it can not be accessed via local PC or via remotely.

don’t know the problem, but due to this problem, i can not access it remotely

i have done port forwarding OK AFAIK (its 8888)