iPad Apple ID verification failed - specific wifi network

Hi,

I’ve been using my iPad for the last 2 years on the same wifi network and all of a sudden I’m having all kinds of issues connecting to any Apple service. I have several other Apple products connected to this network and they are unaffected. When I tried to sign out of my Apple ID or iCloud, or try turn off find my iPad it wouldn’t allow me to and I kept getting the message about Apple ID verification failed. I was then able to reset my iPad by connecting it to my computer / holding down power and home a few times. This allowed me to erase all content and set the iPad up as a new device again. However, I got the same message when trying to sign in on the initial setup using my Apple ID. I tried another Apple ID but same issue. I then disconnected from wifi and used a hot spot connection off my phone and low and behold, everything worked. But as soon as I connect back to the wifi network I get the same problem. All of my other devices work fine so I’m not sure if this is a wifi specific issue or something to do with Apple? Can anyone please help?!?