How to stop getting DNS errors, using Virgin Mobile globesurfer 2?

I’ve bought Virgin Mobile GlobeSurfer 2, first day I’ve connected it and it worked fine, but after few days, I’ve decided to put the modem to another room , from that time it stopped working, every time I connect it to my PC via LAN or WLAN I always getting DNS error (DNS server isn’t responding). Sometimes I can connect to the internet for a few secconds, but it starts to show DNS error.
Modem interface shows that everythings fine(It’s connected to the internet and network is fine).
Even I can’t connect to the internet using my mobile phone connecting to the modem Via WLAN.

The modem is fully unlocked, IMEI isn’t blocked. Modems software have the latest updates.

Any suggestions?