when it comes to networking, ONLY trust dlink or linksys.
for myself im using linksys router/modem thats served me for many many long years (3-6? years give/take or more, i have to check my router's start up/updated firmware date)
for you, it could be other reasons, and power adapter issues are barely the modem's issue itself and can be easily replaced so long you match the socket that plugs into the modem and the voltage required (my dlink router's power adapter failed and i replaced it a few years back, and no problem at all. i replaced it with some random HP power adapter that i bought from LYP too

)