No internet on Cellphones

My Fiber internet has been working fine but the failed. Openserve then sent a SMS to say they know there is a problem but will fix it. Then it came back on and worked fine on my Laptop, however all the cellphones and TV box cannot connect. It connects but within one minute the line is dropper (Cant get IP address or Couldn't Authenticate connection). I phoned Mweb various times and they convinced me to buy another Router which I did. I installed it and it worked fine for 24 hours then had the same problem. The "Tech Specialist" then contacted me but he could not help, basically left me on my own!!