Brand New Mac Won't Accept Wifi Password

I just received a brand new MacBook Air today from the Military Exchange and right out of the box I have nothing but problems. The main problem is that the laptop recognizes my Wifi but will not take my password. It does the same thing with my iPhone personal hotspot. I have never had this issue with my Windows or Android devices, my TV, and not even with my iPhone. I did the reboot of the computer and the router multiple times and I know for sure my passwords are correct. My router is a Viasat satellite receiver. I am seeing all kinds of "fixes" on the net, but none of these should be necessary with a brand new unit. I also can't change the date and time even when logging in with my new Mac password, but that's an issue for another time. Please, someone, tell me there is a simple fix for this. If it's a long complicated process, I will just return it and get a Windows unit. To have problems right out of the box is unacceptable. Thanks for your time.