Virgin Media Hub 3.0 vs Zyxel Multy X

Hi,

I have 2 Multy X's, and a Mini in my mesh network. One Multy X is connected to a Virgin Media Hub 3.0 which has Modem Mode enabled.

I pay for the VM 500mbps package. In non Modem Mode I'm seeing at least 350mbps+ wirelessly. As soon as I switch to Modem Mode, and connect devices to the Multy X mesh network, the most devices are seeing is 90mbps.

Anyone else experienced this issue? Been reading about and people are saying disabling DPI, or IDS/IPS has fixed the issue for them.

Where and how would I go about doing this please? I've checked the VM router settings, and Zyxel router settings but can't see anything related.

Many thanks