Do you actually own that /48? The problem with using the globally routable addresses internally is that your public /48 might change in the future, and and that will force you to change a bunch of internal stuff.
I have my router set up to advertise two /64 prefixes on each LAN subnet: one from fddd:deca:fbad::/56* that I use for all internal communication, and one from 2001:5a8:xxxx:xxxx::/56 that is only used for talking to the internet. Every device I've ever tested supports this configuration flawlessly, including linux/apple/windows laptops, apple/android mobile devices, an IoT vacuum, and a 10+ year old VoIP phone.
My router is a Linux PC, so I can configure radvd however I want (no GUI, I just edit the configs over SSH). Maybe home routers won't let you do this.
* You're really supposed to pick a random prefix in fd00::/8, but uniqueness only matters if you intend to merge networks with somebody else later, I care more about it being easy to remember.
I have my router set up to advertise two /64 prefixes on each LAN subnet: one from fddd:deca:fbad::/56* that I use for all internal communication, and one from 2001:5a8:xxxx:xxxx::/56 that is only used for talking to the internet. Every device I've ever tested supports this configuration flawlessly, including linux/apple/windows laptops, apple/android mobile devices, an IoT vacuum, and a 10+ year old VoIP phone.
My router is a Linux PC, so I can configure radvd however I want (no GUI, I just edit the configs over SSH). Maybe home routers won't let you do this.
* You're really supposed to pick a random prefix in fd00::/8, but uniqueness only matters if you intend to merge networks with somebody else later, I care more about it being easy to remember.