RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

Axo123 · Mon Feb 12, 2024 7:16 pm

Hi, newbie here with RouterOS and having trouble with initial internet setup. Followed the MT 'Getting Started' script mostly to get ether1/WAN to get dynamic IP from Motorola MB7420 Cable MODEM and cannot get Dynamic Client to work... status just stays in 'searching' mode. Must be something very basic I am not doing. Wonder if someone can lend a hand to help me out.

The RB5009 is to replace a TP-Link ER605 that is going bonkers. The ER605 currently connects with the cable modem no problems, but I just can't get the RB5009 to even get info from the Cable MODEM. This is just basic Comcast/Xfinity with dynamic IP, no static IP. I assume if the ER605 can communicate with the MODEM, RouterOS should have a workaround.

Spent 2 days trying tips from this forum, Google and YouTube to no avail, so I have come to get your expert help. I reset the system bunch of times and upgraded to 7.13.4. Below is my current bare bone script...

# 1970-01-02 00:32:26 by RouterOS 7.13.4
# software id = xxxx-xxxx
#
# model = RB5009UPr+S+
# serial number = xxxxxxxxxxx
/interface bridge
add name=LAN-0
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
/ip pool
add name=pool.88 ranges=192.168.88.210-192.168.88.250
/ip dhcp-server
add address-pool=pool.88 interface=ether2 name=dhcp.88
/interface bridge port
add bridge=LAN-0 interface=ether5
add bridge=LAN-0 interface=ether6
add bridge=LAN-0 interface=ether7
add bridge=LAN-0 interface=ether8
/ip address
add address=192.168.88.1/24 interface=ether2 network=192.168.88.0
add address=192.168.0.2/24 interface=LAN-0 network=192.168.0.0
/ip dhcp-client
add interface=ether1
/ip dns
set servers=8.8.8.8,75.75.75.75
/ip firewall nat
add action=masquerade chain=srcnat out-interface=ether1
/ip route
add disabled=no distance=1 dst-address=0.0.0.0/32 gateway=ether1 pref-src="" \
    routing-table=main scope=30 suppress-hw-offload=no target-scope=10
/system note
set show-at-login=no

Mesquite · Mon Feb 12, 2024 9:19 pm

Is that the full config?
Does the TPLINK get a public IP when it connects?
You do not have many of the settings required for subnets to work.
You have no firewall rules.
Your IP route is incorrect etc....

Axo123 · Mon Feb 12, 2024 9:33 pm

Is that the full config?
Does the TPLINK get a public IP when it connects?
You do not have many of the settings required for subnets to work.
You have no firewall rules.
Your IP route is incorrect etc....

That's all the script I have, been resetting and trying to keep in barebone to see why RouterOS is not getting Dynamic IP from the MODEM on ether1
I erase IP Route and still no connection to Comcast.
Believe the TP-Link is getting public IP since I am getting just basic cable internet with Comcast. The TP LInk WAN is set to Dynamic IP connection type but doesn't have 'Get IP using Unicast DHCP' checked. Shows 'connected' with IP address, subnet, default Gateway and the DNS on the TP-Link. TP-Link also can connect via IPv6 Dynamic IP (SLAAC/DHCPv6). I can access the internet via the TP-Link.
Quite stumped why RouterOS is not connecting with barebone or the Default Script. Also tried Quick Set to no avail.

Mesquite · Mon Feb 12, 2024 11:09 pm

Okay I have a similar setup with normal cable and it resolves on its own but I have fiber bell type connection and like yours refuses to work.
The problem in my case is that with routing the gateway for some reason is not getting updated.

Try this......
ON your route give a unique name in comment.
/ip route
add disabled=no distance=1 dst-address=0.0.0.0/32 gateway=ether1 pref-src="" \
routing-table=main scope=30 suppress-hw-offload=no target-scope=10 comment=LuvMyRouter

Then in our your IP DHCP settings...........
Click on the client to pull up the tabs DHCP ADVANCED and STATUS.
Select Advanced. See the text block below.............
Copy and paste in the following:

:if ($bound=1) do={
:local gw [ /ip dhcp-client get $"gateway-address" ]
/ip route set [ find comment="LuvMyRouter" gateway!=$gw ] gateway=$gw
}

Note: just above this text block, set the default distance to 255.

mcisar · Mon Feb 12, 2024 11:39 pm

Hate to post a "me too" post but I'm currently experiencing this exact issue at exactly the same time... so "me too"

Brand new RB5009, on CipherKey (Shaw) Cable in Canada. Router config wiped to defaults and exactly like the OP the dhcp client just sits at "searching...".

Have connected laptop to modem and confirmed that the cable connection is fine and that I do get an IP address in that manner.

My router is on a slightly older version of firmware (whatever version it shipped with 7.11.x if I recall). I normally upgrade firmware to current as soon as the router gets an internet connection.

Larsa · Tue Feb 13, 2024 12:08 am

@Axo123, test if DHCP is working properly by running WinBox "Tools -> Packet Sniffer" on the WAN interface. When the router sends out a DHCPREQUEST, you should receive a DHCPOFFER with an IP address.

As a side note, some sites impose restrictions where you are allowed to use only one IP address which becomes associated with your router's MAC address. And sometimes, for some weird reason, they also introduce a grace period before a new router with a different MAC address can be used.

gabacho4 · Tue Feb 13, 2024 4:15 am

To add on to Larsa's words, you might have to call your ISP to release the MAC lock so that the new router can be used and its MAC address registered. I've had to do that in the past.....good old Comcrap I'm talking to you!

Axo123 · Tue Feb 13, 2024 4:22 am

Okay I have a similar setup with normal cable and it resolves on its own but I have fiber bell type connection and like yours refuses to work.
The problem in my case is that with routing the gateway for some reason is not getting updated.

Try this......
ON your route give a unique name in comment.
/ip route
add disabled=no distance=1 dst-address=0.0.0.0/32 gateway=ether1 pref-src="" \
routing-table=main scope=30 suppress-hw-offload=no target-scope=10 comment=LuvMyRouter
....

Thank you for your mojo! It works finally but really weird. My uneducated guess is it may be issue with the ISP (Comcast) IP lease expiration to get RouterOS to finally talk to the MODEM. Not sure if this is something MikroTik can do something about with RouterOS.

I implemented your command scripts and like magic, I see an IP assigned in the DHCP Client status. Out of curiosity, I backup the working setup containing your script, and restored the standard Mikrotib default script. Without your script, the default configuration also worked. What I noticed was that the ISP Dynamic IP has changed from that on the TP-Link. It also states there are 3 days or so before this newly issued IP lease expires. This seems kinda similar to your system fixing itself after a few days. I rebooted the RB5009 and also the Motorola router several times just to make sure it sticks.

Guess I am keeping the RB5009 afterall, I was thinking I would have to return the MT and settle for another limited function TP-Link router.

Whatever your script did, it may had triggered a change in the ISP IP, something the MODEM itself cannot initiate. Thanks you greatly

Axo123 · Tue Feb 13, 2024 4:35 am

Hi Larsa + Gabacho4, thanks for taking your time to help. Haha, guess the packet sniffer may be too advanced for me right now, but since I am keep the RB5009 given it now connects to the Internet, I will lean RouterOS soon enough

Mcisar, hope the solution to your router issue is similar with mine !

Mesquite · Tue Feb 13, 2024 5:57 am

Without the script every time your IP changes I suspect it will remain stuck, so keep the script in place.

jaclaz · Tue Feb 13, 2024 2:58 pm

Only to try and understand the whole stuff:
1) the router has a DHCP client on ether1 (WAN) connected to the ISP:

/ip dhcp-client
add interface=ether1

the ISP assigns via DHCP to the ether1 an IP address and a gateway

2) the main route points to ether1 as gateway

/ip route
add disabled=no distance=1 dst-address=0.0.0.0/32 gateway=ether1 pref-src="" \
    routing-table=main scope=30 suppress-hw-offload=no target-scope=10

3) for *some reasons* when the ISP changes the IP address of the gateway, the change is not reflected on the route and/or on the ether1 inteface that keeps using the previous gateway address

4) the script checks that the "current" gateway provided by the ISP is used in the main route

5) after the script has been run the route will not have anymore:
gateway=ether1
but rather
gateway=w.x.y.z
where w.x.y.z is the IP address of the gateway retrieved by the:

/ip dhcp-client get $"gateway-address"

The script is a better implementation (checking that the current gateway is not already there) of the script talked about here:
viewtopic.php?t=173560

Do I get all this correctly?

Is the issue caused by incorrect ISP actions/ISP DHCP Server or by Mikrotik DHCP client implementation?

Axo123 · Wed Feb 14, 2024 7:05 am

.......
Is the issue caused by incorrect ISP actions/ISP DHCP Server or by Mikrotik DHCP client implementation?

Wondering why Mikrotik doesn't just embed an ISP dynamic Gateway check similar to the script that Mesquite and the post you shared suggested?

If the very low-end TP-Link ER605 router I have is able to handle over 2 years of changing ISP dynamic IP+gateway, RouterOS may need a minor refinement under the hood. The posting you shared was started in March 2021... so it's an existing know issue.

RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)

Re: RB5009 not getting DynamicIP from Comcast Cable MODEM (Solved)