I am about to put my Virgin Hub 3 which currently has a Lan IP address of 192.168.0.1 into Modem Mode and connect my Vigor2927ac via WAN port 2. As I have a largish number of devices with fixed IP addresses on my system, they are currently set up with gateway addresses of 192.168.0.1 Quest I have is - I dont want to have to change all of these device Gateway settings, can I set the Lan address of my Vigor2927 to 192.168.0.1 once I have connected to the Hub 3. I dont want to cause a network crash with clasjhing IP addresses. And secondly do I leave the DNS settings for the Fixed I devices on the system as-is, eg Virgin Hub gives DNS settings as 194.168.4.100 and 194.168.8.100 currently. I assume these will be the values I also need to set up in the Vigor DHCP server.

Anybody? I think it will be OK but dont want to risk upsetting everything on the system.

BruceWA wrote:
... can I set the Lan address of my Vigor2927 to 192.168.0.1 once I have connected to the Hub 3.

Yes.

When you put the Hub 3 into 'Modem Mode', the 192.168.0.1 address will disappear (because the Router section is disabled) and the Hub 3 will only be accessible via 192.168.100.1 (That's a DOCSIS standard/requirement I believe) - so there won't be a clash. You should still be able to access the Hub 3 on 192.168.100.1 (for management purposes), because it intercepts traffic which the Vigor will be sending to the VM Default Gateway (obviously only for that one address).

And secondly do I leave the DNS settings for the Fixed I devices on the system as-is...

If you don't specify any DNS addresses, the Vigor will probably get them via DHCP (and set them to the values you've given). I think that (by default) the Vigor will give its own address as DNS server, to its LAN Clients (though it seems to act as a transparent DNS cache, whether you want it to, or not).

You might want to look at using alternative DNS servers (such as OpenDNS or Quad9 ), for a bit of extra security. Last but not least, you could have a look at https://www.grc.com/dns/benchmark.htm and see how they all compare, performance-wise.