Warzone issues call of duty

ok so 2 separate accounts (activison) different emails ones my sons and one is mine , we both cant play warzone at the same time in the same house ? iv even tried to do this via hot spot off my phone whilst he’s on the home WIFI still get the same messaged UNABLE TO CONECT TO ONLINE SERVERS . but when the other ones cone off the game the other person can connect straight away Any help appetited and I will pay for a fix