Virgin Media Hub 3.0, modem mode and ports

I ran into a very interesting issue with my Virgin Media Hub 3.0 after moving to a new apartment.

The Hub doesn’t do enough for my liking, so I run it in dumb modem mode and have some more advanced equipment doing the heavy lifting. This works great, and before the move I was happily getting my 300/50 connection speed running over wifi.

After the move, I was only getting 85/50. I first found this when on wifi, but duplicated the speeds with a wired connection. Connection speeds within the network were just fine, so the issue had to be with the internet connection itself.

It turns out that the problem was between my gateway and the Hub 3.0 cable modem. When you linked the two with an ethernet cable, you could see the network light on the gateway slowly blink green as it tried to negotiate a 1Gbps connection. This took a few seconds to fail, at which point the light turned orange to indicate a 100Mbps connection was being used. But everything was working just fine at the old place, so what was going on?

The first thing I checked was the gateway’s port settings. I made sure that it wasn’t set to 100Mbps compatibility and saved the settings. Even after force provisions and reboots, nothing changed.

The next thing I checked was the cable. I was using a 50cm Cat-7 cable, which should have no problems with a 1Gbps connection. But even after trying a different Cat-7 cable and a Cat-6 cable, nothing changed.

There were no settings in the Hub that I could change either. That left only the ports on the back of the device.

Depending where you look, you’re told that when the Hub is in modem mode, you’re supposed to plug your gateway into either port 1 or 4. I had been using port 1. I tried using port 4, but that wasn’t even trying to connect.

Out of desperation, I tried port 2. Success! The gateway’s link light immediately turned green and showed the fast flicker of network activity. Speed tests on both wired and wifi connections showed that everything was running at full speed again.

I can’t see any possible reason why port 2 would be needed here. The Hub 3.0 will only give out a single public IP address when in modem mode, so it doesn’t make sense to have multiple active ports on the back of the device. Any if port 2 is needed, why did port 1 work but only after failing back to 100Mbps?

None of this makes sense to me. However, the internet is working properly again and that’s all that matters.