Alright, run through and try everything that’s been mentioned here. @dave27 mentioned AX mode and I can affirm it connects in AX mode on 2.4G band,** NOT 5G band.**
The challenge is all these routers handle it a bit differently.
Auto on the asus enables all modes, but then lets you disable B and G (and probably N on the AX models).
When you select “N/AX” only on the asus it actually doesn’t disable all the slower rates, but tries to deny older devices from connecting.
Without going into the SSH CLI and verifying what it has set under each mode, it gets very confusing. So may want to try both “auto” and maybe “AX Only” or “N/AX Only” modes.
Did that also include special characters?
MANUALLY REBOOT ROUTER AFTER EVERY CHANGE Some routers (like mine) are PITA divas and will troll you to no end if a reboot is missed)
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@dave27 Good point, can’t be affirmed universally.
I actually have it set N/AX with B disabled on my asus and did not know it operated in that manner. Thanks! Will have to check later.
I just don’t understand because in November it worked with the same router settings.
One more question. If I press and hold the setup button for 10-20 seconds, does it not do the same thing as when I delete it from the profile? Does it do a full reset?
I also don’t understand the free Wyze subscription! I don’t have any subscription, none of the paid options work, but I can play back recordings unlimitedly without a 5-minute limit. 
Can someone tell me how this is possible?
Do I have to remove the SD card when I press the reset button for 10 seconds?
Yes you need to remove the SD card when you factory reset the camera. Have you checked these threads for a possible solution?
It seems that only the guest wifi network does not want to work for some reason.
Bot the camera and your phone have to be on the same network, guest W-Fi in your case.
but why should it be on the same network? The point of guest is that the devices cannot see each other. Sadly It only works only on guest network if wpa2 is configured. 
That is the only way to have the camera set up. Once it is setup you can remove the phone from guest network.
I don’t understand. If the wpa2 is configured not on the same network, it will still connect.
I’m sorry, I’m not sure I understand the above.
When WPA2 is set on the guest Wi-Fi network, the phone is not on the same network, yet the connection is still established. However, if the encryption is set to WPA3, the connection does not establish.
I’m guessing your router doesn’t properly assign WPA3. My router assigns WPA3 to v4 and WPA2 to V3 cameras. I don’t have any issues viewing them locally or remotely. Did you check the links I posted above?
No, I haven’t checked the link yet. Yes, but the strange thing is that the issue only occurs on the guest network. If I connect to the main Wi-Fi, the connection is established without any problems. However, for security reasons, it would be better to use the guest Wi-Fi.
Probably a good idea.
When you connect to the main network the connection is local/direct from the camera to your phone. When on a guest network the connection from the camera loops out through internet to connect to your phone. That is your issue, you have something blocking your connection. I’d suspect it is a security feature on your router. Read the provided links and follow what other people have done and report back.
Yeah I learned with my old AC Asus that auto with “disable B” is the only way to actually disable the slower rates (either below 6M or below 12M, I forget which). “N/AC Only” doesn’t do what you expect it to.
Which guest wifi are you using?
On Asus, Guest Wifi 1 uses a totally different model than Guest Wifi 2 and 3. 1 uses VLANs and different subnets, one VLAN and subnet per band, at least when you have “access LAN” disabled, which I’m assuming you do. 2 and 3 use the same subnet as your main LAN and no VLANs, it just uses a combination of firewall and client isolation to prevent communication between the wifi SSIDs. I’ve found other oddities with the different guest networks behaving a bit differently with other “behind the scenes” settings too.
It shouldn’t matter whether you are set to WPA2 or 3, if both devices aren’t on the same subnet during setup you can have problems. As soon as setup is complete, you can move the phone back to main LAN. I suspect some of the confusion may be coming from the different behavior of the guest networks, and the fact that not all the settings for the guest network are fully in place before you reboot the router. So maybe when it worked on WPA2 that was a coincidence and you hadn’t rebooted yet. In some cases it is even necessary to temporarily enable LAN access to get IOT devices set up, but I haven’t found that to be the case with these cams.
To make matters more confusing, different models of cam use different processes. Some have bluetooth in them and can utilize that during setup, some do not and require the QR code. I believe one will work on different networks and one won’t, but I can’t recall if I’ve ever tried. To avoid doubt, during setup, you want both devices on the same SSID just to be safe.
Get your router set up the way you want it, reboot it, put the cam and phone on the same wifi and go through the setup, see how that works.