Is it the modem or router that responds to BQM pings?

If you are running with a separate modem (or a router in bridge mode) and router, which device is responding to the pings?

I had always assumed the modem. However the ZyXel VMG1312-B10A I am using in bridge mode does not have ICMP enabled for WAN traffic, which I seem to recall was a necessity to get the necessary BQM ping response on my VMG 8924-B10A, when used as a combined modem/router.

My BQM responses have also lost the overnight long grass effect overnight, once I swapped the 8924 (router only) for a Netgear Orbi router.

I suspect I have answered my own question because the above evidence suggests that it has to be the router responding, which somewhat bears low my original assumption!

The device that has the IP address assigned to an interface, so it will be the device doing the routing functionality.