I came across a bug once with a WLAN card where it was dropping inbound DSCP marked packets and symptoms were parts of the Internet didn't work, ended up finding all Internet traffic coming back via Vocus marked with DSCP 0x20 were dropped while Spark Global-Gateway was not marked and could download fine. On a ping/traceroute this would look like an upstream provider problem as for affected hosts everything was good up until about hop 5 where everything would time out if coming back via Vocus. So it's possible it could be an intermediate issue along similar lines, although it is stated here a D-Link router was also tested 🤷‍♂️