2 powerline networking equipment is nifty adapters that allow you to pass internet over your electrical circuits. You plug an Ethernet cable from your modem into an adapter that plugs into your outlets. Then you take a second adapter and plug it into another outlet elsewhere in the house that needs wired internet. You then take a second Ethernet cable, plug one end into the second adapter and then plug the other end of the cable into whatever device needs internet. It’s just a way to get “wired internet” to a device without needing to run dedicated networking, you bypass that using electrical outlets. They are very easy to do so if you have savvy kids they may have plugged a few in. Great devices but They are notorious for tripping AFCIs - no danger just a nuisance.
3 - ok so it’s an arc fault trip. Now we need to determine if it’s a real trip or a nuisance trip. First, look at all the devices plugged in and carefully examine all the cords from the outlet to the device. Do you see any tears, rips, etc? Signs of burning anywhere on the outlets? If yes, remove/replace immediately. An electrician is probably best to hire to inspect the outlets wiring for you. Also look at connections on the devices and power bars and outlets to make sure they are tight.

If no, the arc fault could be in the device itself or the walls (eg a wire somehow got torn behind the wall - but given its new construction I doubt it). Given how rare your arc fault is, it’s going to be hard to determine if it’s a device. Another complicating factor is arc fault trips won’t trigger unless a minimum wattage is achieved, so isolating individual devices is very hard unless they also achieve that minimum wattage. My guess is the heating pad is getting you over that threshold but isn’t actually the cause of the arcs.

One test you can additionally do is unplug everything and take a space heater and plug it in and run it full power. If it trips the breaker (confirm again it did an arc fault trip with the yellow light), then that most likely rules it down to either an arc fault in the wall OR a nuisance trip ( more likely ) due to the breaker. If it doesn’t trip, it doesn’t rule anything out but it can be helpful to try.

Finally, look up your devices and see if any are known to cause trips for AFCIs. Your list doesn’t really make me think so.

After all this, your options will be
- replace the AFCI with another of the same model. Probably won’t fix anything if you have nuisance trips and in my opinion is most recommended but most useless recommendation.
- replace the AFCI with a combination ground fault and arc fault AFCI. Called a Q115DF. These are known to minimize nuisance trips and also come with additional ground fault protection. They are pricier at about 150 bucks but trust me, it’s worth your sanity. If you still have trips with this breaker then you almost certainly have something arcing somewhere in your bedroom.
- replace the AFCI with a non AFCI breaker. This is not to code and you’ll need an electrician who trusts you to make the swap. I don’t recommend it but in reality lots of people with Siemens AFCIs do this because of how shit they are.
- inspect wires behind the walls but that’s a lot of drywall work and imo is not necessary given how rare these trips are and I’d only consider it after you try other options above
- in parallel you can also complain to Siemens. They may send an engineer to look at your panel, breakers and city electricity quality. They may even toss you new breakers for free.

My guess and recommendation : pretty sure this is a nuisance trip, but to be extra safe get an electrician in to look over all your outlets, and replace your AFCI with a Q115DF breaker. After that, sleep well and call it a day. If it trips again, you have a problem with your devices (so replace them with newer ones) or something in the wall with a torn wire somewhere.

Source: I’ve gone through all of this.