Does the device you're trying to get a 2.4ghz connection on also have 5ghz, and you're trying to get it to connect to 2.4 only for some reason? It's difficult to force a choice with the way Google has integrated the 2 channels into their wifi, they leave it to the device to choose the best frequency/channel.
To understand the issue better, you could try putting some kind of wifi monitor app on your phone, one that shows the 2.4 & 5ghz signals and their channel, you'll get an idea of the strength of each at various distances from your wifi signal. Personally I use Wifi Monitor:
As an update for you all, I wanted to let you know that we have a firmware update coming out now. Some people may have already received the update, but most will see it coming still. Everyone will have it before the end of April. If you receive that update and don't see an improvement in your issues here, please let me know and we can keep looking into things.
It does happen automatically, you can't manually apply it. You can see your current software version by going into Google Home and opening your router device, then click the gear icon top right for settings, and it's under "Wifi information".
By now everyone should have the update. If you are seeing issues, try restarting your network via power cycle and see how things run from there. If the update hasn't installed yet, it will after the power cycle, so if it takes a while to boot up, just wait it out. Let me know if you aren't seeing improvements at this point.
I'm having the same issue. The home automation device gets the wifi information from my mobile device. Because I can't connect my mobile device via 2.4 to the Nest, I can't see the device I need to connect to. I just got Nest Wifi to replace my old network, but I've spent hours trying to get my smart home devices set up but doesn't look like it's possible. So it's going back. What a terrible design. I can see the 2.4ghz signal in wifi analyzer, but can't connect to it.