Wifi not connecting after Altice box update

Ever since the optimum Altice box had a software/firmware update a few weeks ago, my Simplisafe system has not been able to connect to wifi.  I am guessing it's because the box used to broadcast distinct  2.4Ghz and 5Ghz signals, but now it transmits a "combined" signal... whatever that means.  My Simplisafe system has been working well for months with this same Altice box, but not it's not.  What can be done to fix this??