Sorry for the delay, too much going on recently. Once I had a chance to do some more digging, turned out it did seem to be some kind of power settings, with the box "sleeping" after short periods of idle time. The box is headless, but none of the lights indicated this and it was extremely fast to come back up after sleep. I never found any settings for this in the GUI, and disabling powerD didn't help, so I just installed from scratch since I was seeing other issues anyway. It's resolved now. I hope this was abnormal (new user to pfSense and the first time I've upgraded; I hope most upgrades go more smoothly than this).
doktornotor, thanks for the reply, I guess. I'm new to pfSense and not a networking expert. Maybe it's not an ideal setup, but I'm willing to learn, and open to constructive feedback. To answer your questions, WAN is a cable modem, no PPPoE or anything going on. I went the bridge route because it made sense for the hardware I had at the time and I figured I could add a switch later if needed. I've read it's not ideal, but haven't seen downsides mentioned other than performance, which is not affecting me for now; if you have more to add, or why you think this issue would be at all related to the bridge, please do so, so others can learn. Snort was something new to play with since I haven't had the opportunity before, which I may not keep. I like the proxy because not all of my devices can run Privoxy natively.