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Gr8Britton's profile

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Tuesday, March 15th, 2016 5:00 PM

New Mikrotik Router will not route Internet traffic

We currently have a Netgear WiFi Router that connects to a Comcast Internet with a Static IP and then to our Netgear Switch. I have added a Mikrotik CRS as another switch and that is working fine. I have purchased a Mikrotik Routerboard 1100AHx2 which I would like to use to replace the Netgear as our main Internet router

 

Using the QuickSet, I setup the WAN side with the exact same static IP, Subnet, GW and DNS servers as the Netgear and gave it the same IP address on the LAN side. I checked to bridge all ports and checked NAT. I removed the Netgear and replaced it with the RB and I could access it via the MAC or IP using Winbox just fine. Using the tools, I could ping from the RB to anything on the LAN side and on the WAN port of the RB. However, it will not route anything over the Internet. DNS servers do not resolve and I cannot ping the DNS server

 

If I remove the RB and put back the Netgear, I'm able to ping the DNS servers, Google and etc.

 

For more detail, I will use the following fictitious IP scheme:

Internet Static IP: 1.1.1.1
Internet Subnet: 255.255.255.252
Internet GW IP: 50.251.69.122
DNS: 75.75.76.76 | 75.75.75.75

LAN Static IP: 192.168.1.1
Subnet: 255.255.255.0
GW: 192.168.1.1
DNS: 192.168.1.10 (File/Print/DHCP/DNS server)


To initially setup, I use QuickSet and set it up with:

 

Internet (Our Current LAN Network)
IP: 192.168.1.3
SN: 255.255.255.0
GW: 192.168.1.10
DNS: 192.168.1.10

 

LAN (A new network)
IP: 192.168.2.1
SN: 255.255.255.0
GW: 192.168.2.1
DNS:

Check DHCP (192.168.2.100-192.168.2.199)
Check Bridge All Ports
Check NAT


When I do this, I connect my laptop to one of the router ports and I get 192.168.2.100 and am able to ping all assets on the 192.168.2.x and 192.168.1.x networks. Also, I am able to browse the web and perform ping/traceroute to google.com. All is good.


I then turn off the Internet modem and current WiFi/Router. I change the Routerboard to:
Internet Static IP: 1.1.1.1
Internet Subnet: 255.255.255.252
Internet GW IP: 50.251.69.122

DNS: 75.75.76.76 | 75.75.75.75

LAN Static IP: 192.168.1.1

Subnet: 255.255.255.0
Uncheck DHCP
Leave NAT checked

 

Everything on the LAN side works great but I cannot do anything past the WAN port on my router, which is set to my static IP.  I check my routes, and all is good EXCEPT the 0.0.0.0/0 route that is using the Comcast gateway of 50.251.69.122, which reports as unreachable.  I even tried spoofing my MAC address to be the same as the Netgear but that did not work.

 

Anyone have any suggestions?

Accepted Solution

New problem solver

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4 Messages

9 years ago

Since you are doing NAT, have you set up your firewall rules for NAT? You need to build some rules in there to accept traffic.

 

Take a look at http://wiki.mikrotik.com/wiki/Manual:Initial_Configuration to get you started.

Advocate

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1.4K Messages

9 years ago

Hello Gr8Britton and welcome,

 

I am not exactly sure what your actual connection is but I will provide some trobleshooting recommendations.

 

First, your Mikrotik CRS (MCRS) must be directly plugged into any of the Comast Gateway (CG) LanPorts 1-4.  I am presuming that you have programmed the MCRS WAN interface with your Comcast Static IP routable,gateway, subnet mask addresses and included the correct PriDNS=75.75.75.75 and 2ndDNS=75.75.76.76. Now the Mikrotik RouterBoard (MRB) is installed into your MCRS, correct? Have you done any configuration of the MRB for it to have access to the correct Comcast StaticIP addresses mapping?

 

You should be able to first ping and receive replies from anywhere on the internet your CG Static IP Gateway address to know that your CG is functioning correctly. Next you need to ping and receive replies from your Static IP routable address to make sure your Static IP device is programmed correctly and available on the Internet.

 

Now some issues I saw that need to be corrected:

1. Internet (Our Current LAN Network)
IP: 192.168.1.3
SN: 255.255.255.0
GW: 192.168.1.10
DNS: 192.168.1.10


Your DNS cannot have the same IP as the GW ! Change the DNS to 75.75.75.75. Your IP: 192.168.1.3 should always be IP: 192.168.1.1

 

 

2. LAN (A new network)
IP: 192.168.2.1
SN: 255.255.255.0
GW: 192.168.2.1
DNS:

Check DHCP (192.168.2.100-192.168.2.199)
Check Bridge All Ports
Check NAT

 

Your IP: 192.168.2.1 cannot be the same as your GW: 192.168.2.1 ! Also add the DNS = 75.75.75.75

 

3. I then turn off the Internet modem and current WiFi/Router. I change the Routerboard to:
Internet Static IP: 1.1.1.1
Internet Subnet: 255.255.255.252
Internet GW IP: 50.251.69.122

DNS: 75.75.76.76 | 75.75.75.75

LAN Static IP: 192.168.1.1

Subnet: 255.255.255.0
Uncheck DHCP
Leave NAT checked

 

Your Internet Static IP should be 50.251.69.121. If you plan on using your Local LAN DHCP you MUST make sure that DHCP is checked for correct functional operation.

 

Please let the forum know if I have misunderstood your networking interconnection, however, the troubleshooting recommendations and issue corrections stand fast.