Router sends DHCPDISCOVER when it shouldn't.

RouterOS General
1

Hi,
I’m stuck with finding why my router RB750Gr3 (7.16.1) is sending DHCPDISCOVER all the time.
I noticed that there is a constant flow on DHCPDISCOVER with source address of ether2 interface on that interface
I have bridge with vlan filtering and multiple vlans on this interface.
There is no dhcp-client set on that interface, and this is inded router sending those packages since hostname in that packet matches my router hostname.
What is going on ? :slight_smile:
It looks like this:

 3 time=1.025 num=4 direction=tx src-mac=CC:2D:E0:07:84:E1 dst-mac=FF:FF:FF:FF:FF:FF vlan=73 interface=ether2 src-address=0.0.0.0:68 (bootpc)
   dst-address=255.255.255.255:67 (bootps) protocol=ip ip-protocol=udp size=346 cpu=3 ip-packet-size=328 ip-header-size=20 dscp=0 identification=0 fragment-offset=0
   ttl=16

 4 time=1.046 num=5 direction=tx src-mac=CC:2D:E0:07:84:E1 dst-mac=FF:FF:FF:FF:FF:FF vlan=74 interface=ether2 src-address=0.0.0.0:68 (bootpc)
   dst-address=255.255.255.255:67 (bootps) protocol=ip ip-protocol=udp size=346 cpu=3 ip-packet-size=328 ip-header-size=20 dscp=0 identification=0 fragment-offset=0
   ttl=16

 5 time=1.056 num=6 direction=tx src-mac=CC:2D:E0:07:84:E1 dst-mac=FF:FF:FF:FF:FF:FF vlan=302 interface=ether2 src-address=0.0.0.0:68 (bootpc)
   dst-address=255.255.255.255:67 (bootps) protocol=ip ip-protocol=udp size=346 cpu=3 ip-packet-size=328 ip-header-size=20 dscp=0 identification=0 fragment-offset=0
   ttl=16

 6 time=1.077 num=7 direction=tx src-mac=CC:2D:E0:07:84:E1 dst-mac=FF:FF:FF:FF:FF:FF vlan=71 interface=ether2 src-address=0.0.0.0:68 (bootpc)
   dst-address=255.255.255.255:67 (bootps) protocol=ip ip-protocol=udp size=346 cpu=3 ip-packet-size=328 ip-header-size=20 dscp=0 identification=0 fragment-offset=0
   ttl=16

 7 time=1.077 num=8 direction=tx src-mac=CC:2D:E0:07:84:E1 dst-mac=FF:FF:FF:FF:FF:FF vlan=70 interface=ether2 src-address=0.0.0.0:68 (bootpc)
   dst-address=255.255.255.255:67 (bootps) protocol=ip ip-protocol=udp size=346 cpu=3 ip-packet-size=328 ip-header-size=20 dscp=0 identification=0 fragment-offset=0
   ttl=16
2

There’s service “detect internet” which in theory helps to set router correctly for people who don’t fiddle with manual settings (too much), but has potential to screw things up … One of mechanizms is using DHCP client procedures even on interfaces where DHCP client is not configured.

So check settings under /interface/detect-internet. My recommendation is to disable the functionality altogether if you configured LAN and WAN manually because detect internet can still interfere. You can do it by setting all interface lists to none .

3

Spot on !

That was it. I never heard about that feature.

Thanks!