Okay, so this iPhone works as expected with different routers? That’s good news.
Then the next step is rebooting the Wi-Fi router, and rebooting the iPhone. That’s cleared weirdness.
Then checking that the Wi-Fi connection is WPA2 and not WPA, WEP, or cleartext, and that the router is at current vendor firmware version.
Also the local network configuration, as there are at least three different (related?) Wi-Fi networks using variations of that same name. That can cause problems with connectivity, if those (inter-related?) networks aren’t correctly configured, and potentially also correctly subnet’d.
A Wi-Fi router from the past dozen or more years should have support for WPA2.
Which Wi-Fi vendor, and which model? We might be able to run some searches for further details.