vodafone net getting disconnect after 10-20 seconds.

​i bhought inspiron 3420. with specification intel core i3,2gb ram & 64 bit os with windows7.previously i use hcl desktop. problem occur in net connection.i use micromax modem for net. when i use vodafone 3g in dell laptop net getting disruted after 10-20 seconds.then i have to disconnect & reconnected it. problem is repated.but when i use same modem with my old desktop,, vodafone net goes very well. no disrupten. my destop and laptop is in same room. so vodafone network problem does not come into account. pls give me a solution about this problem.​