So as bridged modem my HH5A consumes something like 6.9 W on average (see here) (both WiFi radios disabled).
In my limited experience the HH5A (in 2018 IIRC) did already struggle on a 50/10 link with NAT, firewall, SQM, WiFi, speedtests over WiFi stayed well below the expected throughput. I reluctantly relegated it to bridged-modem duty, which it now does satisfactorily on a nominal 100/40 link (VDSL2/PTM sync 116.797 Mb/s / 36.999 Mb/s, full bidirectional throughput is a bit behind the theoretical limit, but fast enough for me not to bother, YMMV).