Ethernet connection between two independently powered routers - will it work

Hi all, my first question:

Building an offgrid house and am part way through the process. As a temporary solution I have a number of solar PV panels powering some little charge controllers, batteries and inverters. My security camera system is powered by one inverter/battery/CC/PV system and my computers and router by another inverter/battery/CC/PV system.  And all works fine.

But I want to connect my security system to the router so that means plugging an ethernet cable between the two systems.  As the two systems have no common earth/neutral/battery can I do this? 

yes

Thank you! That was blindingly quick!

But, if you do actually mean 2 routers, you need to turn off dhcp on the secondary router, and basically use it as a switch.

depends if its connected as another switch or if router 1 is connected to WAN port of router 2

Ethernetnet is differential pair data communications and hence isolated from all the power. 

Your solution will work fine.

It is very much unlikely that the camera will have configuration for DHCP so do not switch off any DHCP.

Andy™ said:

depends if its connected as another switch or if router 1 is connected to WAN port of router 2

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calltronics said:

Ethernetnet is differential pair data communications and hence isolated from all the power. 

Your solution will work fine.

It is very much unlikely that the camera will have configuration for DHCP so do not switch off any DHCP.

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I was just confirming, as per the thread title.

I have 6 x  'routers' / 'modems' in my house simply being used as switches

calltronics said:

Ethernetnet is differential pair data communications and hence isolated from all the power. 

Your solution will work fine.

It is very much unlikely that the camera will have configuration for DHCP so do not switch off any DHCP.

Click to expand...

I always understood that 2 or more dhcp servers on the same network would cause issues, so surely with two modems both with dhcp, you would have to turn one of them off, I have turned dhcp off on my NAS & my managed switch and just use the dhcp on my Draytek router, and all works fine.

Sidewinder said:

I always understood that 2 or more dhcp servers on the same network would cause issues, so surely with two modems both with dhcp, you would have to turn one of them off, I have turned dhcp off on my NAS & my managed switch and just use the dhcp on my Draytek router, and all works fine.

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That's exactly what i have done, my Draytek issues everything (barring fixed IP equipment) with an address, and I've just used cheap (free) ISP supplied routers/modems as switches, and simply turned dhcp off on them, works great. 

Ahh, now I use the Draytek to lock mac to ip and prevent access unless previously allowed, this locking down both wifi & wired within reason, so the only way to gain access is with an already registered mac address, as well as the wifi ssid & password.

My 

calltronics said:

Ethernetnet is differential pair data communications and hence isolated from all the power. 

Your solution will work fine.

Click to expand...

That was the info I wanted, thanks

Sidewinder said:

Ahh, now I use the Draytek to lock mac to ip and prevent access unless previously allowed, this locking down both wifi & wired within reason, so the only way to gain access is with an already registered mac address, as well as the wifi ssid & password.

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I have a totally separate network set up on mine for guests, it only allows for access to WAN, and not LAN,  the wife's mates son used to moan all the time as he couldn't connect as i had a load of (the known ones to me) apple addresses blacklisted, so his iCrap phone kept getting no access, :slap

Edit : guests still need to know the guest WiFi code btw, it's not an open network. 

Apologies I did try to attach a rough circuit diagram but as a new user I could not.  I now can.  For this temporary solution only one of the inverters has an earth connection, so no option to 'common up' (if I understand the term correctly).  I hope to try it today

steptoe said:

I have a totally separate network set up on mine for guests, it only allows for access to WAN, and not LAN,  the wife's mates son used to moan all the time as he couldn't connect as i had a load of (the known ones to me) apple addresses blacklisted, so his iCrap phone kept getting no access, :slap

Edit : guests still need to know the guest WiFi code btw, it's not an open network. 

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Yes, I have a guest WAN only set too.

It isn't open either, but it is still MAC locked, so I have to grant access & give out an ip.

ReadiesCards said:

Apologies I did try to attach a rough circuit diagram but as a new user I could not.  I now can.  For this temporary solution only one of the inverters has an earth connection, so no option to 'common up' (if I understand the term correctly).  I hope to try it today

View attachment 8015

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OK, so you are using 2 routers, 

You need to make sure only the 'master' , or primary router is set to dhcp , do you have any model numbers,? 

I'm glad to report it works. i.e. two totally separate powered systems (with no shared earth/ ac neutral/dc- connections) are communicating over a LAN ethernet connection without any black smoke arising. Phew!

ReadiesCards said:

I'm glad to report it works. i.e. two totally separate powered systems (with no shared earth/ ac neutral/dc- connections) are communicating over a LAN ethernet connection without any black smoke arising. Phew!

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Until it goes wrong, which hopefully it won't but, working under normal conditions is fine, just make sure that you have it covered so that it doesn't get fried under fault conditions.

Sidewinder said:

Until it goes wrong, which hopefully it won't but, working under normal conditions is fine, just make sure that you have it covered so that it doesn't get fried under fault conditions.

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Simplest way to do that is use fibre.