I've read this thread with interest.
I have tried 2 Gen 3 Telstra modems on my farm property, which is stuck on old DSL with a connection speed of about 7 mbps down, 1 mbps up. One is brand new as at 2025.
Funnily enough, the slow connection is surprisingly useable when I'm on a Telstra Gen 2 (DJA0231) because the latency is quick. I can play WoW, Starcraft etc. Even Netflix is OK! There's no internet optimiser from Telstra for its DSL services, so it's just plain vanilla internet.
On the Gen 3 I get HUGE lag spikes at irregular intervals, Gaming pings will go from 220 ms (normal in Australia to US servers) way up to 3000+ ms - sometimes for 20 seconds, often enough to disconnect. There's no line dropout, no loss of sync, nothing I can see in the logs.
So - to the Netduma folk watching - I don't know exactly what you think you fixed in 2024, but in 2025 there's still a major screw loose. A shame, too, because the Gen 3 is a nice bit of hardware that I'd like to upgrade to.