Virgin Media in the UK currently offers a "Gig1" service that offers ~1.2Gbps down and 50Mbps up.
While the topic of mediocre upload speed is valid, that is a discussion for another time.
While the interface on the HFC interface offers 1.2Gbps downlink bandwidth, the Hub 4 modem itself offers only 4 x 1GbE interfaces, essentially limiting the usable downlink throughput to GbE (in practice ~940Mbps).
This bloc post covers an undocumented feature, which allows aggregation of multiple GbE ports on the Hub 4, and create a WAN connection that is capable of >GbE speed.
WARNING: While the bonding is stable with this firmware on Hub 4, the Round Robin (and alb as well) seem to fail for no reason every now and then. This does not seem to be ready for production use.
Date tested: 2021-01-31
Model: Virgin Media Hub 4 (ARRIS TG3492LG-VMB)
Hardware Version: 8
Software Version: 01.02.065.21.EURO.PC20
Model: Mikrotik RB4011iGS+
Firmware Version: v6.48
On the ISP Modem side - no configuration needed.
On the CPE, I created a new bond with the following configuration: