Modem+Router issue

Hello, heres my problem, i have a d-link modem wich is very good and never disconnects, on the other side i have this damm modem from the brand of god knows what that my service provider installed. This modem disconnects from internet a couple of times a day, but when it does it disconnects and then connects disconnects and connects for about 5 minutes, even if i reset it. My past modem burnt out and before it burnt it disconnected just like this one does... Should i replace it? Is there any test i can make?

Thanks a lot....

It could be the modem or it could be your connection to the ISP. If the D-Link router is fine and you're having issues I would call your ISP. If it is the Internet connection or the modem it should be their issue to fix.

Im in the same situation you are in my modem started to shut down and restart as of recent a technician from my isp came today and told me i had an old modem that mine was 3 models old so he gave me a new one. My internet is stable but it did disconnect one but after that one time its been fine the whole day. Talk to your isp and tell them whats going on it will be a long hold on the phone but i told them exactly what you wrote here for my situation and so far so good.