Internet goes out every night at 6pm(ish) until 10am(ish)

12/1/20 new wireless service. 12/11/20 no service and was told it was an outage and not known when it would be fixed. I phone, I chat, paper trail. 12/17 chat, I explain internet will only connect between 10am & 6pm, not before or after & I am told the outage has been fixed. We discuss tech coming out and charge if the issue is on my end vs no fee if it is on their end. I’m on a fixed income due to disability . I’m also enrolled in classes next semester, I need internet. So we schedule a tech. Tech comes out and informs me it is probably because I am still using my router and my modem is wireless. Ok, great. Remove router and tech is out in about 10 minutes at 3:10pm. 7pm, no internet. Again with the chat, I’m told to go to store re to exchange for new modem. Done! 6pm NO INTERNET! Up until the very day I plugged in the new modem, I had minor issues with my 4 year old modem and router. So here I sit on Christmas Eve with no freakin internet!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!