My grand strean keeps desconecting it self.

i have a granstream 502 adapter it keeps desconecting it self,but is no new is just now is more often, since i sing up with voipo desconnects one a week now is doing this three times a week i keep pluging out the power so it connects again.
i try to make a call and never gets connected after a minute sound busy or just get silence air
things i have done poen port fowarding on the router
connected direct to modem
change the network cable
plug only one phone to the dapter.
have firewall off on the router
change internet provider
change router.
this getting nme crazy the way my incomming calls are getting connected now is with a obi110 fowarding the calls when the divice fail to the obi number.
already sent another tiket to costumer support let see what they can do but this is getting frustrating:mad:
thanks guys if someone knows a way to fix this please let me know.

finally fixed i already have a week with no problems, the issue was my modem from century link.
I was able to put it on bridge mode and all issues have been fix no more desconnections . i just want to let you know on case you have the same problem.