I just had the same issue. Once you finished putting everything together, installing ink cartridges, etc. and get to the wireless set up, throw the manual away. It is useless.
I tried it the manual's way, got the 5 GHz error message and thought what? My router uses both. In fact, if your router broadcasts at 5 GHz, it most likely does at 2.4 GHz as well. The problem is most routers made in the past 10 years will allow your device to switch between them based on speed. There's two options, the wrong one is first
1 (don't do this). You can turn off smart select or whatever your router calls it and it will then broadcast as two routers, one at 2.4 GHz and one at 5 GHz. Then you can use the software on your computer or smartphone to connect the printer as described in the manual. However, now whatever device you want to print from must also connect to the same network, which kind of ruins the point of having a router that allows you to move between frequencies to improve overall speed. So don't do this.
2 (Do this!). Leave your router alone. Throw away the manual. Use the little screen on the printer to set up your wireless network. Instead of easy mode or whatever, just pick manual. It will list your wireless networks just like on your phone and computer. You then enter the password. Takes like 10 seconds. The printer has no issues connecting to a router that switches between 2.4 GHz and 5 GHz. It just picks the 2.4 GHz signal. Your computer, however, was probably on the 5 GHz signal for speed reasons and that caused the issue.
Hope that helps someone. They should just rewrite the manual to not use their strange installation software and just use the neat little screen that they provided. Works great!
Also, kind of annoying that you can't exit the installation software without killing the process. Once I realized what was going on I couldn't get out of the installation loop. Hooray for task manager!
