I've beeing using a J1900 based firewall appliance with pfSense for a while and it's been great until I moved from VM to Zen over FTTP. It would cap out around 400-500mbps and suffer heavy packet loss as it hits the limit.
Based on a recommendation, I picked up an PC Engines APU2 to replace it and that's worse.
It seems there's a particular issue with PPPoE and Intel nics in pfSense, but ultimately the hardware doesn't seem powerful enough to do PPPoE at these speeds anyway, as it the J1900 still "only" does 500-800mbps with Linux based ipfire.
I haven't tried a Linux based solution on the APU2, but I suspect it'll be a similar story.
I see 3 options;
1. Try OpenWRT which will probably run on anything
2. Get better suited, more powerful hardware to keep running pfSense.
3. Find an off the shelf appliance
The trouble is, I can't find too much information on proven solutions.
Goodbye Hyperoptic. Now VM200