I don't have any specific recs - I've just seen desktop motherboards with 2.5Gb/s and my boring standard AT&T fiber box has a 2.5Gb/s LAN port on it.
If you're already running a device like that Protectli then maybe you'd be comfortable building a small-form-factor PC with a 2 port 2.5Gb/s ethernet card (around $40) and running it to a 4-port 2.5Gb/s switch (around $125 for this TRENDnet one I see on Amazon). You could even install PFSense on the PC and keep your setup mostly unchanged.