No one will explain why my phone keeps changing on WiFi connect

I was told by customer service last year that my WiFi had been hacked and I needed a new router so they sent one. Then I was told again recently that I needed new equipment with "better security" and a tech came to my home and switched the gateway again. 

Every time I connect my iPhone to my WiFi, it is listed with a weird black box icon and not a phone icon and is named "generic Apple device" or "Apple device" or "misc device" and I get a text and an email Every Single Time I connect my phone to tell me a "new"'Apple device is connected to my network, even though I haven't asked WiFi to forget the device.

When I finally went into my actual gateway admin panel, the device doesn't even match what my phone says.

And at one point, when WiFi was identifying my phone correctly (sometimes it does, the last time was a couple weeks ago), it was telling me my iPhone wasn't connected to WiFi but another "Apple device" was, and when I paused that device, it paused my phone. Wifi and the app do not identify the device type, iOS, or name of my iPhone. 

If I connect my old iPhone to WiFi, it tells me the iPhone model, iOS version, and nickname I assigned it, plus it doesn't show "misc device" or a weird black box icon, it shows a phone icon. 

Why isn't this working with my actual current phone?

Why is it constantly saying a "new" device is connected when I haven't connected a "new" device?

And why can nobody at customer service explain why or what's happening, not even the tech who came to my home and switched the gateway?

Nobody will explain it, even though my old devices are all connecting normally and identified correctly, and when people visit me, their devices are all identified correctly too.