Computers & Electronics

Connecting cable modem to DSL Modem

  • Last Updated:
  • Dec 23rd, 2020 10:36 pm
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton

Connecting cable modem to DSL Modem

I know that one can connect the cable modem to a DSL modem by putting the cable modem in bridge mode and reconfiguring one of the LAN port on dsl modem to WAN port.
However, I was successful in connecting my CGN3U cable to dsl modem RG505N without doing either of the above steps. It worked fine except that the websites that I had visited recently would time out. Sites not visited recently open up fine.
is this due to re-building of dns cache?
Secondly, I am unable to connect my PC directly to cable modem (no connection to dsl modem). It just does not let me surf. I have tried ipconfig release, renew commands but for some reason PC does not connect to internet. POPO did not help either. Is there any other trick I can use?
15 replies
Member
Dec 6, 2020
378 posts
354 upvotes
Your use of terminology is too confused to tell what you're trying to do or how to make it work for you.

What is the problem that you're ultimately trying to solve?
Deal Expert
User avatar
Mar 25, 2003
16047 posts
4551 upvotes
Markham
Why not just get a router?
96TB Mediasonic H82-SU3S2 / 72TB Raid 50 on Mediasonic H8R2-SU3S2
48TB Node 304 / i5-3570 / Server 2016 Essentials
12TB HP Mediasmart EX 495 (E8400, 3.0GHZ, 4GB Mushkin), with Server 2016 Essentials
16TB Qnap TS-459 Pro
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton
Keigotw wrote: Why not just get a router?
I do have Asus and TP link router but need a part of network to use DSL modem as a router because of existing Parental controls.
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton
middleofnowhere wrote: Your use of terminology is too confused to tell what you're trying to do or how to make it work for you.

What is the problem that you're ultimately trying to solve?
The second part of question has been taken care of.
Now, All I need to know is can I use dsl modem as a router for a segment of home network while connecting it to a cable modem which will be only modem connecting to ISP. DSL modem will not have any connection to ISP.
Deal Addict
Sep 13, 2011
1033 posts
660 upvotes
Canada
luking wrote: The second part of question has been taken care of.
Now, All I need to know is can I use dsl modem as a router for a segment of home network while connecting it to a cable modem which will be only modem connecting to ISP. DSL modem will not have any connection to ISP.
If you want help, be clear, that a very confusing description.

Are you trying to use your dsl modem-router as a router only while having only a cable ISP ?
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton
elgros4 wrote: If you want help, be clear, that a very confusing description.

Are you trying to use your dsl modem-router as a router only while having only a cable ISP ?
exactly
Deal Addict
Sep 13, 2011
1033 posts
660 upvotes
Canada
luking wrote: exactly
I don't know wich model you have, but I think it would not work to use as a router only.
Deal Expert
Aug 2, 2004
33564 posts
7236 upvotes
East Gwillimbury
@luking

Very confusing.

Get rid of the DSL modem. If you want to set parental controls, install AdGuard Home on a Raspberry Pi and use it to filter DNS. Then use your cable modem to set time restrictions based on IP address.

I am guessing that your DSL modem has time restriction features that you want to use. You can also restrict login times directly in Windows 10

Open an elevated command prompt and enter

net user luking /times:m-f,09-17;sa-su,10-16

Replace luking with the appropriate user name. The above example restricts login from 9-5 Monday thru Friday and 10 am to 4 pm on weekends

By hooking up your DSL modem to your cable modem, you are asking for a whole lot of trouble. First there is the double NAT issue, second, if they are both on the same subnet, you may encounter IP conflicts. Finally, it is never good to have multiple DHCP servers running
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton
Gee wrote: @luking

Very confusing.

Get rid of the DSL modem. If you want to set parental controls, install AdGuard Home on a Raspberry Pi and use it to filter DNS. Then use your cable modem to set time restrictions based on IP address.

I am guessing that your DSL modem has time restriction features that you want to use. You can also restrict login times directly in Windows 10

Open an elevated command prompt and enter

net user luking /times:m-f,09-17;sa-su,10-16

Replace luking with the appropriate user name. The above example restricts login from 9-5 Monday thru Friday and 10 am to 4 pm on weekends

By hooking up your DSL modem to your cable modem, you are asking for a whole lot of trouble. First there is the double NAT issue, second, if they are both on the same subnet, you may encounter IP conflicts. Finally, it is never good to have multiple DHCP servers running
ha ha you got it. I am using different subnets so that avoids the double natting issue but after an hour or two, the two router modems are sharing the route info so every few hours I lose the internet connectivity to the recently opened sites.
So unless I put cable modem in bridge mode and follow instructions on https://www.dslreports.com/forum/r31449 ... able-modem, it is going to be a constant headache.
Hopefully asus router 66U has enough parental controls for me to get rid of the dsl modem altogether
Deal Expert
Aug 2, 2004
33564 posts
7236 upvotes
East Gwillimbury
luking wrote: Hopefully asus router 66U has enough parental controls for me to get rid of the dsl modem altogether
You still need to put your cable modem into bridge mode to use the Asus.

No matter what you do, you need to have the cable modem in bridge mode. The problem with the DSL modem is that it requires / wants PPPoE to establish a connection.

The proper way to configure your current setup is to use the cable modem in bridge mode. You don't need to worry about subnets when you do this as it disables DHCP on the cable modem. Now all you need to do is plug in a cable from LAN Port 1 on the cable modem to LAN port 1 on the DSL modem. Don't use the WAN port on your DSL modem.

That should do it. Unless your specific DSL modem requires the PPPoE to function. Chances are, you don't have a WAN port on the DSL modem, just a telephone jack
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton
Gee wrote: You still need to put your cable modem into bridge mode to use the Asus.

No matter what you do, you need to have the cable modem in bridge mode. The problem with the DSL modem is that it requires / wants PPPoE to establish a connection.

The proper way to configure your current setup is to use the cable modem in bridge mode. You don't need to worry about subnets when you do this as it disables DHCP on the cable modem. Now all you need to do is plug in a cable from LAN Port 1 on the cable modem to LAN port 1 on the DSL modem. Don't use the WAN port on your DSL modem.

That should do it. Unless your specific DSL modem requires the PPPoE to function. Chances are, you don't have a WAN port on the DSL modem, just a telephone jack
Chances are, you don't have a WAN port on the DSL modem, just a telephone jack - Yepp.
Thanks for the excellent reply. i think you saved me from next headache. I guess I will have to put cable Modem in Bridge mode (and forget about its wi fi capability) , connect it to a 66U router (and use router's wi fi) and then connect a switch or a hub to router in order to connect multiple hosts via ethernet to the switch. i can even connect the dsl modem to the switch and it will happily provide its wi fi and ethernet access.
Correct? (Please write yes)
Deal Expert
Aug 2, 2004
33564 posts
7236 upvotes
East Gwillimbury
luking wrote: Thanks for the excellent reply. i think you saved me from next headache. I guess I will have to put cable Modem in Bridge mode (and forget about its wi fi capability) , connect it to a 66U router (and use router's wi fi) and then connect a switch or a hub to router in order to connect multiple hosts via ethernet to the switch. i can even connect the dsl modem to the switch and it will happily provide its wi fi and ethernet access.
Correct? (Please write yes)
Back up the truck.

Who said the WiFi would not work in bridge mode? If you use the DSL modem as a router, you should still be able to use the WiFi on your cable modem. The 4 port switch will still work, everything will continue working except the router.

You don't need the Asus router. Just put the cable modem in bridge mode, connect the DSL to the Cable modem via LAN ports. This will give you 3 remaining ethernet ports on each modem. You will be able to use the WiFi on the cable modem and the DSL router.

If you need more ports, connect a switch to either the cable or DSL modem. If you want to use the Asus router, then set the Asus to AP (Access Point) mode
[OP]
Sr. Member
Mar 6, 2010
521 posts
171 upvotes
Brampton
Gee wrote: Back up the truck.

Who said the WiFi would not work in bridge mode? If you use the DSL modem as a router, you should still be able to use the WiFi on your cable modem. The 4 port switch will still work, everything will continue working except the router.

You don't need the Asus router. Just put the cable modem in bridge mode, connect the DSL to the Cable modem via LAN ports. This will give you 3 remaining ethernet ports on each modem. You will be able to use the WiFi on the cable modem and the DSL router.

If you need more ports, connect a switch to either the cable or DSL modem. If you want to use the Asus router, then set the Asus to AP (Access Point) mode
Excellent. Can't thank you enough for being clear, concise and so helpful.
Deal Addict
User avatar
Oct 14, 2010
1385 posts
822 upvotes
Barrie ON
Gee wrote:
No matter what you do, you need to have the cable modem in bridge mode. The problem with the DSL modem is that it requires / wants PPPoE to establish a connection.

The proper way to configure your current setup is to use the cable modem in bridge mode. You don't need to worry about subnets when you do this as it disables DHCP on the cable modem. Now all you need to do is plug in a cable from LAN Port 1 on the cable modem to LAN port 1 on the DSL modem. Don't use the WAN port on your DSL modem.
I'm certainly not an expert on these things, but I know the HH2000 has a WAN port. I also know that when you configure the HH2000 you are given the choice of Auto, ADSL, VDSL, and WAN Ethernet.

My understanding is that when PPPOE is selected (ADSL & VDSL), then the HH2000 modem looks for data on the RJ11 phone port. When Ethernet is selected it will look for the public network on the WAN port.

I have also always assumed that when an ISP modem/router is placed into "bridge mode" that it only acts as a modem, and the router functionality is disabled. In effect it modulates and demodulates (i.e. modem) the data to/from the ISP, and outputs the raw ethernet data on one or more LAN ports.

In this case, connecting a LAN port from the "modem" to the WAN port of the second router, would be the correct connection to make. The second modem/router would be configured for a dynamic address on the WAN port if the ISP is a cable provider, and it would be configured for PPPOE if the ISP is a DSL provider. This is certainly the method I am using from my HH2000 to my Edgerouter.

Please feel free to correct me if I am wrong.

PS I still don't know what the OP is trying to accomplish. Perhaps rather than asking if he can connect LAN ports to WAN ports, he should describe his overall goal. I don't know if he is a parent trying to setup parental controls, or he is a child trying to bypass parental controls.
luking wrote: I do have Asus and TP link router but need a part of network to use DSL modem as a router because of existing Parental controls.
Deal Expert
Aug 2, 2004
33564 posts
7236 upvotes
East Gwillimbury
Rick007 wrote: Please feel free to correct me if I am wrong.

PS I still don't know what the OP is trying to accomplish. Perhaps rather than asking if he can connect LAN ports to WAN ports, he should describe his overall goal. I don't know if he is a parent trying to setup parental controls, or he is a child trying to bypass parental controls.
You're correct that the Home Hub 3000 has a WAN port. That is why I originally stated that he may or may not have a WAN port.

The Home Hub still uses PPPoE, the WAN port is used to bridge the GBIC for Fibe. My guess is that @luking has a DSL router and not a Home Hub. It really depends on his DSL router he is using. If it requires PPPoE to function as a router, he maybe out of luck, but not all ISP uses PPPoE and it may work like a cable modem. He didn't specify the model of the router.

Here is what I think he is trying to accomplish

He has cable internet, so he must use the cable modem
He likes the WiFi on the cable modem and want to continue using it
He wants the features of the DSL modem that allows him to set time restrictions based on IP/MAC address for his kids. For this to work, the DSL modem must be the DHCP server

Top