Can I connect the output of a modem to the output of a router

[Dre4873]

I was told by someone that I can connect an Ethernet cord from the output of a modem to the output of a router and that works making it a switch. I don't believe that is accurate. Any insight?

 

[getochkn]

Routers don't have output, only inputs.

 

[Dre4873]

Output as in LAN ports. From the output of the modem to the lan port of a router

 

[getochkn]

Yes but you have to disable a bunch of the router functions and assign it an ip, etc.

Why don't you just plug the modem into the WAN port of the router though, unless it's a modem/router combo you are talking about.

 

[Dre4873]

To be more informative... It's a modem router. Has 4 lan ports. Can you connect and Ethernet port from the lan port of the modem router to the lan port of the additional router to use as an access point. Not extremely networking savvy but I know an ok amount and I always thought that caused issues like internet dropping or intermittent.

 

[getochkn]

Yes you can go modem/router LAN to router LAN, but you have to disable a lot of the router functions to make it work, since you just want to use it as a switch.

 

[Dre4873]

I do cable phone internet for work. I have a customer telling me that is ok. I told him it wasn't ok and switched it. He insisted it fine and switched it back. Needless to say I'm going back there today to try to fix his internet problems. Again. He has Ethernet going from lan of modem router to LAN of external router. Also out of combo he has an Ethernet going to another router in basement and another going to a switch. Out of router in question he also has another Ethernet going from loan to somewhere else. Not sure where tho

 

[getochkn]

it's fine, I have about 5 routers chained together over my house, but I have disabled DHCP on each of them and assigned each router a IP outside the range of the main routers DHCP.

A router takes the internet from the modem, and then assigns internal IP's to each device connected. This is the DHCP. Now if two routers are connected together and the seconds ones DHCP isn't turned off, then both routers are trying to assign IP's and they will conflict.

 

[jsmithepa]

I do cable phone internet for work.

Doesn't sound like you understand the LAN side of things, are you sure you want to make your company liable for this portion of the customer's equipment?

In the States, the ISP guy is only responsible that Internet is available at the modem and the rest of it he doesn't touch.

 

[getochkn]

I do cable phone internet for work.

Doesn't sound like you understand the LAN side of things, are you sure you want to make your company liable for this portion of the customer's equipment?

In the States, the ISP guy is only responsible that Internet is available at the modem and the rest of it he doesn't touch.

Same here, no one touches our routers when they come in. They install the modem, plug in a laptop, test connection and speed and leave. Anything else after that is your own doing. If the internet works at the modem, than the ISP has done their job. If I called my ISP to come out complaining about connections and they came and had to config my 5 routers, I would get a $400 bill for service.

 

[jsmithepa]

OK, you are doing this for a friend, YES you can hook up a modem's output to the router's LAN port just to use it as a switch, but as mentioned, you also will have to disable a bunch of stuff at the router. The router's LAN ports, working as a switch are neither IN or OUT, they are IO. This would be a non-standard configuration, but it's do-able.

 

[Dre4873]

I dont touch any of his stuff. Thats the problem. Any settings he has i cant control and its not a normal modem router. It controls all his other boxes that require an ip to work. But i have to go back when his internet or video gets knocked out from his stuff. But he doesnt accept that he is wrong