Slow after switching to Modem Mode



I have just had M350 FTTP installed with virgin, the Hub 3 was set up and working with speeds 300Mb+ on Wifi. Anyway I want to put in on my existing network so switched over to modem mode and temporarily used a 5Mtr Cat 6 cable to connect a single port on the Hub3 to my WAN port of my ASUS RT-AC88U.

In the router, I changed the connection mode from PPPoE to Automatic IP, it connected straight away.

The issue is I then ran a speed test on my PC and the speed was now about 20Mb Down / 4Mb up (Previously 300Mb / 35mb).

The light on the Hub 3 is Red but this appears normal for Modem Mode and when I looked in the hub 3 status page things looked normal as far as I could tell.

Has anyone had an issue when switching to Modem mode and adding to an existing system with massive speed drops?

I think its the router settings for the virgin connection (Previously on FTTC I was getting 50Mb/15Mb), I have restarted the Hub3 Modem and Asus, I don't want to factory reset the Asus as I have a mesh network set up and about 80 devices that connect many with mac address > Fix IP.

Any Ideas?



Active Member
are you running any custom firmware on the ASUS RT-AC88U like DDWRT

I have such a setup with a Tenda AC 15 running the Tomato firmware and get 350 down/30 up


Well-known Member
I don't know what is causing your issue but I had RT-AC88U with 500Mb VM connection and it was to cope (just about) even with all the logging and management switched on.

I don't know how many fixed IP you have but make a note of the fixed IP, drop the DHCP lease time to something like 10 minutes and reset and update the firmware on the router. I have about 15 fixed addresses and it took less than 15 minutes to re-enter them all.

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