- If the ISP modem has a built in router, it's best to bridge the modem. Having 2 routers on the same line can cause connection problems: Link>Double NAT and How NAT Works. Call the ISP and ask to see if the ISP modem can be bridged. To tell if the modem is bridged or not, look at the routers web page, Status/Device Info/Wan Section, if there is a 192.168.0.# address in the WAN IP address field, then the modem is not bridged. If the modem can't be bridged then see if the modem has a DMZ option and input the IP address the router gets from the modem and put that into the modems DMZ. Also check the routers DHCP IP address maybe conflicting with the ISP modems IP address of 192.168.0.1. Check to see if this is the same on the ISP modem, and if modem can't be bridged, change the DIR router to 192.168.1.1 or .0.254.
Example of a D-Link router configured for PPPoE with ISP Modem bridged: PPPoE Configuration on a Router
Information for users with Arris ISP cable modems:
1. Arris modems seem to be notorious for not working well with external routers. One reason, some of the Arris modems already have a built in router. These modems can't be bridged like DSL modems. In some cases, and if the Arris modems Web page is accessible by a user, and if the modem has a DMZ option, a user could input the external routers WAN IP address it gets from the Arris modem into the Arris modems DMZ. This will help bypass any Arris modem management and processing and should open up everything to the external router. I have seen some cases that ISPs lock down the Arris modems web page from users. In this case I would contact the ISP and see if they can help with setting up the DMZ for use. Is some cases, changing out the Arris modem for a different mfr modem is preferred, depending upon if the ISP allow customers to bring there own modem or not and if a customer has Voice Phone services thru there ISP which requires the use of Arris modems. If any one of these options can't be resolved for using an Arris modem, then it's recommended that D-Link users either >Turning a router into an AP,
or connect a D-Link DAP model AP device in which these models do not have a router however provides WiFi and wired LAN connectivity to devices. These DAP models can be connected to a host based router or Modem/Router combo as seen with Arris modems and will let the ISP modem do all the routing functions rather than trying to get 2 different routers to work gether which will introduce >Double NAT
and causes connection problems.
DLink DAP models are some of the following: D-Link DAP 1360, 1513, 1522, 1525, 1533
Other newer models are available as well.
2. In some cases the Arris modems are stand alone modems with out any built in router. In some cases, most of these modems can be connected to external routers and do work well with out any problems. Then some cases we've seen some odd behavior between the Arris modem and external routers that seem to have no resolution. Something thats just not compatible or seems to be an ISP issue. In these cases general connections should work if the Arris modem connects to the external router. Sometimes MAC Cloning can be used on the external router to make the connection work well between the Arris modem and external router. Other troubleshooting may need to be one with the ISP. Checking LAN cabling between ISP modem and external router also helps. >Cat6 is recommended.
Shortest length possible is preferred. Sometimes line signal levels from the ISP service box to the customer building needs to be checked. Also using TV line splitters will lower line levels to the ISP Modem thus making the entire system not work well and makes customer think it's the routers fault when the problem lies upstream from the router and with the ISP service, lines and modem. We recommend that you have your ISP check the cabling going to the ISP modem, check signal levels going to the ISP modem. For DSL or Fiber service lines, ensure that the ISP is using good working phone or cable lines to the DSL modem and that the phone lines are filtered correctly. For cable Internet, RG-6
coaxial cable is needed, not RG-59
. Check for t.v. line splitters and remove them as they can introduce noise on the line and lower the signal going to the ISP modem. We recommend having the ISP service physically check the lines going from the out side to the ISP modem. Connecting to the ISP modem could result in a false positive as the signal to the modem could be just enough to that point then adding on a router, could see problems. The router operation is dependent upon getting good data flow from the ISP modem and the modem is dependent upon getting good signal from the ISP Service.
Over all, if you can avoid using Arris modems as your ISP modem and use something else is preferred. Motorola/Arris SB 6 Series
modems are very good and work very well with D-Link routers. If the Arris modem and external router are connecting and working well for you then you should be good to go. Just be aware of the above mentioned items. Check with the ISP and check here in the forums about getting some information and help. We are here to help you get it working as best as we can, however if we can't, other alternatives will need to be investigated.