DHCP Client searching on new RB750gr3

RouterOS Beginner Basics
1

I just got an RB750gr3 to replace an RB750 from ~2012. DHCP Client is stuck on searching and does not appear to be connecting to the modem. The old RB750 that is being replaced was also connected using the default automatic DHCP Client settings and it did and still connects without issue. Comparing DHCP Client settings between the 2 devices they appear the same. RB750gr3 is using the default automatic settings, which it will most likely need to remain automatic since the ISP may change my IP when the modem reboots.

I checked the NAT masquerade setting per the Wiki and that appears normal as well. I updated to the latest rOS 6.37.1. I did a factory reset after the update. The WAN to modem is connected to ether1 which lists as DHCP Client connection. The main difference I saw was the additional filter rules set in the Firewall section. Also ether1 flashes between reachable and unreachable. What might be different between the two default setups that I am overlooking?

Below is an export after another fresh reset. I do notice that in the old Router I have ether1 showing in the interface and in the gr3 it shows as ether1 discover=no, is that the issue?
Thanks,
old rb750
/interface ethernet
set [ find default-name=ether1 ] name=ether1-gateway
/old rb750

jan/02/1970 00:00:57 by RouterOS 6.37.1

software id = 7UAR-6585

/interface ethernet
set [ find default-name=ether2 ] name=ether2-master
set [ find default-name=ether3 ] master-port=ether2-master
set [ find default-name=ether4 ] master-port=ether2-master
set [ find default-name=ether5 ] master-port=ether2-master
/ip neighbor discovery
set ether1 discover=no
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp disabled=no interface=ether2-master name=defconf
/ip address
add address=192.168.88.1/24 comment=defconf interface=ether2-master network=192.168.88.0
/ip dhcp-client
add comment=defconf dhcp-options=hostname,clientid disabled=no interface=ether1
/ip dhcp-server network
add address=192.168.88.0/24 comment=defconf gateway=192.168.88.1
/ip dns
set allow-remote-requests=yes
/ip dns static
add address=192.168.88.1 name=router
/ip firewall filter
add action=accept chain=input comment="defconf: accept ICMP" protocol=icmp
add action=accept chain=input comment="defconf: accept established,related" connection-state=established,related
add action=drop chain=input comment="defconf: drop all from WAN" in-interface=ether1
add action=fasttrack-connection chain=forward comment="defconf: fasttrack" connection-state=established,related
add action=accept chain=forward comment="defconf: accept established,related" connection-state=established,related
add action=drop chain=forward comment="defconf: drop invalid" connection-state=invalid
add action=drop chain=forward comment="defconf: drop all from WAN not DSTNATed" connection-nat-state=!dstnat connection-state=new in-interface=ether1
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" out-interface=ether1
/system routerboard settings
set memory-frequency=1200DDR protected-routerboot=disabled
/tool mac-server
set [ find default=yes ] disabled=yes
add interface=ether2-master
/tool mac-server mac-winbox
set [ find default=yes ] disabled=yes
add interface=ether2-master

2

I set discover = true on ether1 and that had no effect. Still at a loss here.

3

Is your modem a transparent bridge?
Some ISP DHCP servers have a timeout when MAC address changes and you need to be patient in that case.
When your ethernet port does not link correctly, check the cable or you may have a compatability issue between
the modem and router.
I am using an RB750Gr3 with very good results since last week.

4

I will give that a try when I am home, though I have connected my laptop directly to the modem without issue. Modem is an Arris Surfboard SB 6183

5

The rookiest of mistakes! It was in fact the cable. However the cable itself is fine, as it was what I had used for the last 4 years with the old router. It does not have markings on it to indicate if it is cat5 or 5e, but a speed test maxing at 90mbps would indicate cat5. Should the modem to router connection work with just cat5? I thought they would autodetect and set to 100Mb instead of 1Gb.

Either way, it is working now, thanks!

6

Speed autodetection only covers the capabilities of the endpoints, not the quality or length of the cable.
If your cable is bad, you need to replace it or set the appropriate speed manually, AT BOTH ENDS.
(one end at fixed config and the other at autodetect will be an even bigger disaster)