RB450G / Comcast Modem

Good Day Everybody,

I am having an issue with a RB450G and a Comcast Modem. The modem has built in DHCP so if you plug devices in directly there is at least some kind of internet connection. The modem is also setup to route specific IP’s which we have 5 static IP addresses. Assuming the modem itself is using one of those 5.

Now I have setup the 5 ip addresses on the RB450G and disabled all but one, things work great, however, we’ve been having issues where the internet just stops working or slows down drastically. When we use Speedtest.net, it shows our IP address, not all the time, but at times as 255.255.255.0 which makes no sense in the world to me.

Does anybody have any idea what could be happening?

We also had an issue with one of the IP addresses where internet kept going in and out and in and out and we did a ping test to that IP from the outside in, and noticed that the IP would respond for about 15 seconds and stop responding for about 25 and then again for 15 and again not for about 25. So I wasn’t sure if the modem was maybe using that IP, so I changed it to another one, and the issue appeared to have gone away.

Can anybody help me, please?

Thanks!

Call Comcast and tell them to put there modem in bridge mode. This will allow you to let the 450G to do all of the work and likely remove the majority of your problems.