2 Modems on same network and IP range. will it work?

Hi,

I have TT fibre (to cabinet) & use TPLink VR600 V.2.

I have a big LAN, multiple routers etc acting as AP's, all works well.

What I would quite like to do is have another,2nd complete fibre provider partially as a backup but also some of this bandwidth on different PC's.

I want every PC still to have access to all the other PC's and web cams & NAS's etc. which is were I believe my thinking will fall down.

e.g.
Modem A - plugged into e.g. TalkTalk BT socket
192.168.2.1 - acting as DHCP

Modem B - plugged into e.g. Sky BT Socket
192.168.2.2 - I assume would need DHCP OFF

PC (1) would be normal using modem (A) gateway as 192.168.2.1 and DNS 192.168.2.1 or 8.8.8.8 etc

if I wanted PC (2) to use modem (B) I guess gateway would have to be 192.168.2.2 but would not then get DHCP. I am guessing can't use gateway .2.1 and DNS 2.2 as DNS is not really the same thing.

As I try to explain I realise this could be really tricky.

Any ideas, I do need LAN access for every device to every other device.

Thanks I/A

I'd have the TalkTalk and Sky devices on different subnets and get LAN devices talking together by setting up a second IP interface on them specifically for the LAN networking.

Things get fiddly though and you'll find yourself forgetting tweaks done to make things work at times.

Better option is to use a load balancer so the two WAN connections go into this and all local devices are then on the same LAN, there are cheap £50 ones but reports of them not coping with lots of devices, so probably would ere more towards things like this Linksys one (https://amzn.to/2ntbm55 £158) if you have lots of devices, and then of course need wireless access points to give wireless access to the LAN.

A case of balancing head scratching and fiddling time going the manual way, or spending money on kit to help do what you want.
On the NAS some may have dual LAN interfaces which would help.

I took the plunge and decided to get an extra line installed into my home last year.

My first line is with Plusnet and my second line is with Vodafone.

I use two HG612 modems and my router runs OpenWRT, one of the LAN ports is configured into a seperate WAN2 VLAN, I then use the MWAN3 package on OpenWRT that handles the dual WAN load balancing.

It works very well for me, and I am very glad that I did this, it has been well worth it and I would probably not be without it, for me the single point of failure is now at the cabinet, but not much can be done about that.

I configured MWAN3 to balance all HTTP/HTTPS connections, with the exception of my banking sites as that may potentially cause some issues with connections coming from multiple IP's.

I do a lot of downloading with Usenet, so my providers allow connection from multiple IP's and any downloading I do in the browser, I either use DownThemAll in Firefox or ensure parallel downloading is enabled in Google Chrome, this then aggregates both connections.

Hope that is of some use!

Hi,

Many thanks for you fast reply,

I did once add a second line & got a TP link 470 load balancing when I was just slow adsl, a few months later, despite saying it would be years before we got FTTC it was enabled!
Gratefully TT let me cancel the 2nd line as Fibre was fast enough then.

However I would prefer now to have a 2nd ISP modem in my business office 100m from where my current ISP BT socket is, partially as backup for phone system & credit card machine etc if I am paying to allow my home speed to be max all the time.

But I need access to the central computer that has my database backend (server).

I might just leave for the moment.

I will have to learn about setting up different subnets etc but as you say I think in the future I am not doing enough and will forget what I have done.

It is partially brought on by my frustration as relatively low upload compared to download & combination of all this I would like a 2nd line to test as well as use.

Still v.fast but I get true test of 75mb down but only 10mb up
Sync up 10993 down 88802
TT are not interested as well within BT test & am 600mb from cabinet so v.lucky but feel this ratio is not right. Do so much uploading with backup etc nowadays every mb counts.
.. but thats another story.

600 metres from the cabinet one would expect a lower download but perhaps a better upload - not massively so though.

The download and upload do not hold their ratio over distance, i.e. there will be times when the download frequencies are more usable than the upload ones due to power masks, cross talk, interference and the more predictable attenuation.

The key to knowing if you have a fault on your lines setup is to see what immediate neighbours manage

You could keep the 2 networks cabled separately but have both of them connect in to network cards on your server (ie install a second card). Use separate subnets on each network and setup network software on the server to handle DHCP and routing between the subnets. You would set the Internet gateway on each subnet to be the appropriate routers IP.

However, this may be a little daunting and could take a while to get setup correctly if you aren't used to do network servers.

100m is the limit for an ethernet cable.

In reply to a post by Michael_Chare:

100m is the limit for an ethernet cable.

Theoretical, with all the joints normally associated with structured cabling. Generally in the home, they can go further, especially as speeds are normally under 100 Mbps.

In reply to a post by MrSaffron:

600 metres from the cabinet one would expect a lower download but perhaps a better upload - not massively so though.

I'm only 470 metres, and my stats:
Max: Upstream rate = 5697 Kbps, Downstream rate = 45832 Kbps
Bearer: 0, Upstream rate = 6443 Kbps, Downstream rate = 47150 Kbps

i would get the VDSL installed in the home office.

1. use a static assigned IP on PC2, router A 192.168.1.1 with a DHCP scope 192.168.1.100 - 192.168.1.254
router 2 192.168.1.2 DHCP off, then on PC2 set the ipv4 setting to

IP = 192.168.1.50
subnet 255.255.255.0
gateway 192.168.1.2
DNS primary 192.168.1.1 secondary 8.8.8.8

all devices on the network will use DHCP and will use router 1

I have read all the answers given and I think you should be able to do it fairly easily on a single subnet. I did this when I had 2 lines both with ADSL. Basically Each line went to a linux box which also acted as a firewall, I also ran a dns server on one of the linux boxes which decided who connected to each line. Both linux boxes were on my internal network.

Snags

1. 2 linux boxes running 24hrs a day (mine were just old computers)
2. had to muck about in the DNS server if you wanted to change a user to the other line.

It was very useful for a period when we had 2 lodgers and limited data (40GB per month) it did also provide lots of redundancy, however now with FTTC we just have the one line, one box running 24hrs a day and all the other computers are shut down when not in use. The saving in Electricity is amazing. We were using aprox 8500 units per year now with solar panels we are down to about 3500. Happily very few glitches on the FTTC line. If that dies now I would try and use the hotspot on my mobile for essential connections.

Draytek allow you to have 2 ISPs and have a feature called Lan IP Alias
So you can manually set some devices on the same subnet with a different gateway.

Have a look here.

https://www.draytek.com/support/knowledge-base/4917