@David-TP In the ongoing saga (starting to sound a bit like Days of Our Lives), I bought a new modem, on recommendation from TPG. It arrived this morning (a TP-Link VX420-G2v AX5400) and it is now up...

@David-TP Well, I've solved part of the problem. I am now back to 750+Mbps from the modem. The problem, I'm embarrassed to admit, was because the laptop I was using to test doesn't have an ethernet...

@David-TP I tried a cat6 cable to connect the modem to the X68. Results were essentially identical (87Mbps for the cat5, 85 for the cat6). I updated the laptop to the latest versions of everything...

I haven't got a cat6 cable so I'll have to get one. The laptop I'm using for testing actually isn't mine, it's a friends, but I can get her to update anything that needs updating. She hardly ever...

@David-TP I did as you suggested, removed the four E4s and tried again. I got some strangely anomalous results. Connecting directly to the modem with a cat5 cable - 154Mbps Connecting to the X68 with...

@David-TP, I tried changing the QOS to 1000/1000. I'm still getting around 130Mbps on wifi from the x68. Is there anything else I can try? Thanks.