Fire tablet on local network only (no internet) issues

I’ve been using the little cheap amazon fire tablets and they work well but I started to lock down my network and one of those things is making sure any HA/IoT thing can’t access the internet unless I let it. I found that because of this the fire tablets wont connect, it appears they try to connect to the internet and if they can’t just stop or go in some loop checking. Has anyone see this, maybe I can open a certain port to make it think it can connect?