It's 2021. IPv6 has been out for 26 years! It's been in common use for 6 years. Square, Stripe, Braintree, PayPal, etc., etc. all support ipv6. Why isn't Authorize.net?
To make it worse, your "techs" don't seem to even know what IPv6 is!
The problem is, modern internet providers are switching their customers to ipv6, so now when those customers place orders on sites using authorize.net, a false/positive is triggered. This makes the fraud suite useless.