Yes, you will loose your wi-fi network configuration, but that is something that could be set up again.
Based on on what I have read, I would strongly suggest a reset.
Look at the back of the modem and see what model it is. There are three CGN3 series modems, CGN3, CGN3AC, and CGN3ACSMR. That will determine what type of reset can be done, and how to check.
In all cases you can reset the modem by depressing the recessed reset button at the back of the modem for 30 seconds and then releasing it. That will initiate a factory reset back to Gateway mode, where the modem acts as modem and wifi router.
When the reset and automatic reboot into Gateway mode is complete, connect a pc to the modem and login by starting a web browser and entering 192.168.0.1 in the address bar to bring up the Modem's login page. You should be able to do this with an ethernet connection. If not, the wifi networks will be up and running. The details of those networks are seen at the back of the modem, and include the network name and default password.
The credentials for the modem login page are cusadmin and password.
After logging in, navigate to BASIC.... GATEWAY FUNCTION, and disable the Residential Gateway Function. Save the data and the modem will reboot into Bridge mode automatically.
While the reboot is going on, disconnect the pc and reconnect it to the router. When the modem reboot is complete, you should only have one device connected to the modem, which should be the router. You can get two IP addresses from the modem when its in Bridge mode, but most people run the rest of the network off of the router.
When the modem reboot is complete it should be running in Bridge mode and the router should be running in full router mode. Restart the router and log into it to check the IP address which should now be 192.168.0.1, and check that its set to run in full router mode if there are various modes available. Those modes should include Router mode, Access Point mode and Bridge mode.
The router WAN port should be connected to one of the modem ports. With a router that has the three modes avaialable as a selection, you would normally connect to the WAN port. You can run a router that doesn't have those selections to run as an Access Point by conneting to any of the LAN ports and setting the DHCP server to OFF, but for this discussion, I think your trying to run a normal modem (Bridge configuration) with a follow on router (in Router Mode)
Can you confirm the router model number as it doesn't show up in the D-Link Canada site.
Thank you again for the in-depth reply, I'll be doing this over the weekend.
The router is a DIR-845L sorry, wrote it wrong in the first post
Thanks. I'll be able to have a look at the user manual now to see how this router is set up.
With the profiles deleted, you should be able to log into the modem, after a factory reset, with a direct ethernet connection so that you can kick it into Bridge mode. After it reboots, with the modem connected to the router's yellow WAN port, you can run a reset on the router as well.
Then with a pc connected to the router via ethernet, you should be able to log back into the router to set it up. Select DHCP connection (Dynamic IP Address) and set up the wifi parameters and you should be ok. With the modem running in Bridge mode and the 845L set up from ground zero, your ethernet connection should work.
The only other thing I can think of is that the IPV4 addresses in the pc and laptop are not on automatic. To check that go START... CONTROL PANEL.... NETWORK AND SHARING CENTER. For the displayed ethernet adapter, right click to bring up the menu and select Properties. That brings up the Ethernet Properties panel. Scroll down to the bottom. Deselect Internet Protocal Version 6 (TCP/IPv6) as it doesn't function properly on the Rogers network, which is a whole other discussion, and then select the bottom Internet Protocol Version 4 (TCP/IPv4) and select Properties just to the lower right. That brings up the Internet Protocol Version 4 (TCP/IPv4) Properties panel. It should be set for "Obtain an IP address automatically" For the DNS you could use the automatic selection, or you could choose to set the DNS server of your choice such as GOOGLE 18.104.22.168 or 22.214.171.124, or OpenDNS 126.96.36.199 or 188.8.131.52. If you wanted to use a different DNS, other than the Rogers DNS, it should be set in the router so that your whole network will use the selected server. Running with the servers set in the pc or laptop will ensure that if the router settings are ever changed without your knowledge due to a rogue program using UPNP in the router, your pc and laptop will still use the DNS of your choice. If you had to change either selection, IP or DNS address, hit OK, close all of the panels and reboot the pc or laptop. If you did change the IP address selection, that change should result in the pc or laptop using the router as its ethernet gateway.
for the past week or two, I have been having a strange problem with my modem(s). Every few hours, the wired connections on my modem all stop working, but the wifi is still working flawlessly. a simple reboot fixes the problem, and the modem and all connections then work great.
I say modem(s), because I'm on my 2nd modem in 2 weeks. The problem happened last week on the CGN3ACR that I had. I called Rogers help, the person factory reset the modem from his end, and set it up, told me to call back if it happened again. I was on the test firmware and already did factory reset in June, but I thought it would fix it. But then a few hours later, the wired connections dropped again. I called rogers help again, and if I remember correctly this person said the controller was off. He told me to go and exchange the modem. I said I would upgrade to Gigabit, so I went to Rogers store and got the CGNM-3552, came back home and immediately asked for the new firmware trial. this modem was only a few hours out of the box and the wired connections stopped working (this was before the new firmware got installed). 2 days later, the new firmware was pushed to my modem, I factory reset it, and it worked great for 2 days, and now my wired connections dropped again. I rebooted and everything works great now.
Is there an explanation, or previous cases of this happening where the modem drops wired connections but wifi still works?
I sort of don't want to call the Rogers help line again, because I might just get the factory reset again, and them telling me to see if it happens again. this problem happened on 2 different modems, so maybe I'm unlucky, but I think it's something else.
info: 4 wired connections are in CAT6:
-Xbox One S
I don't have a router, just the modem.
I am stating that my modem works flawlessly for a few hours or days and then the wired connections drop.
My problem happened on 2 different modems, and the wired connections stop working, but a reboot makes it work again.
the solution posted by datalink does not help me at all in my case.
Also, it's not a DNS problem, as my devices connected to wifi have no problems.
thank you very much for replying.
my current modem CGNM-3552 is on the beta firmware (184.108.40.206) which I have asked last week from the thread to communityhelps.
when you say to ask communityhelps for the beta "newer" firmware, does this imply an even newer firmware than the one from the test thread? sorry for asking but the language makes it seem like I am not on the most up-to-date firmware, and that is a possibility that it could resolve this issue I'm having.