Connecting a new iphone to my router wireless network

[#1]

In case my router is limiting how many MAC addresses I can use, I'm looking at all the MAC addresses listed on my router lists ('Attached', ''Allowed But Not Connected', and 'Blocked') to identify what equipment those MACs belong to. There are a few strange ones:-

1. A Chromcast device that isn't plugged in or powered up, but is still listed on the 'Attached' list - if it isn't being used why is it on the attached list?;

2. A device on the 'Allowed but not Connected' list that I cannot identify, but according to MACvendor.com, it is manufactured by Intel - any ideas what this device might be? Could it be a dongle? I have one connected to an old pc that is set up but hasn't been used for ages - would the dongle still be powered up in spite of the pc being switched off?

[#2]

@RealAleMadrid  and @dvorak Its taken me three weeks to get access to another iPhone that just happens to connect with my wifi, and it turns out that between the two of you, you appear to have solved my problem. RealAleMadrid had the basic answer and Dvorak hasd the correct name. I checked the method of finding the MAC Address on an iphone, and it seems there are two potential MAC Addresses, the first being in the iphone Settings > General > About and the MAC Address is listed in WiFi Address, the second is to go looking for, as Dvorak called it, "Private Address". When I compared both of these with what showed on my modem connections list, the modem showed the Private Address. Therefore what I need to do now is get hold of the ipohone I couldn't get to connect, then find its Private Address and load that on my modem. Hopefully, that will fix this problem.

My thanks to all, and especially to RealAleMadrid and Dvorak - and hopefully I will soon be able to click on "This solved my problem" button when I next have the problem iphone here