Hello colleagues.
I searched for that, but they are only topics related to wireless.
This is my network:
RB750GL (Load Balance) --> RB1100AHx2 (Core router) ---> then, wireless to the clients.
I'm connected directly to the RB1100, tested various cables, and nothing, still have "ping timeout" to several domains.
FYI, two days ago, I had a RB951Ui-2HnD for the core router, but we replace it because the load of the CPU.
We have two networks, 10.0.0.0/23 (for management and CPE) and 10.0.2.0/23 (for clients routers).
Also, we have a slow browsing. So, I tried disabling DNS Cache, but didn't work.
Hope is something bad with the config, because at the moment I'm a little disappointed with the performance of the RB1100 
Filter rules of the core router.
apr/25/2014 11:00:42 by RouterOS 6.12
software id = 7L0L-A3ZV
/ip firewall filter
add action=drop chain=input comment="DNS Flood from WAN" dst-port=53
in-interface=ether1 protocol=udp
add action=drop chain=forward comment="DNS Flood from LAN" dst-port=53
out-interface=!ether1 protocol=udp
add chain=input comment="Established Connections" connection-state=
established
add chain=input comment="Related Connections" connection-state=related
add action=drop chain=forward comment="Drop Invalid Connections"
connection-state=invalid
add action=drop chain=forward comment="Static IP Block" dst-address=0.0.0.0/0
in-interface=ether6 out-interface=ether1 src-address=10.0.2.0/23
src-address-list=!basico
add action=drop chain=forward dst-address=0.0.0.0/0 in-interface=ether6
out-interface=ether1 src-address=10.0.0.0/23
add action=drop chain=forward comment="Block LAN to Ubiquiti Gears"
dst-address=10.0.0.0/23 in-interface=ether6 src-address=10.0.2.0/23
src-address-list=!Admin
add action=drop chain=forward comment="Defaulters Clients" in-interface=
ether6 src-address=10.0.2.0/23 src-address-list=morosos
add action=drop chain=input comment="ICMP Flood Atack" packet-size=128-65535
protocol=icmp
add action=drop chain=output packet-size=128-65535 protocol=icmp
add action=drop chain=forward comment="Virus Filter" src-address=!10.0.2.0/23
src-address-list=Virus
add action=add-src-to-address-list address-list=Virus address-list-timeout=1w
chain=forward connection-limit=400,32 in-interface=ether6 protocol=tcp
src-address=!10.0.2.0/23 src-address-list=!Virus tcp-flags=syn
add action=drop chain=forward comment="P2P Block" p2p=all-p2p src-address=
!10.0.2.0/23 src-address-list="P2P Block"
add action=drop chain=input src-address=!10.0.2.0/23 src-address-list=
"P2P Block"
add action=add-src-to-address-list address-list="P2P Block"
address-list-timeout=1w chain=forward p2p=all-p2p src-address=
!10.0.2.0/23 src-address-list="!P2P Block"
add action=jump chain=forward comment="SYN Flood protect" connection-state=
new jump-target=SYN-Protect protocol=tcp tcp-flags=syn
add chain=SYN-Protect connection-state=new limit=400,5 protocol=tcp
tcp-flags=syn
add action=drop chain=SYN-Protect connection-state=new protocol=tcp
tcp-flags=syn
add action=drop chain=virus comment="Drop Blaster Worm" dst-port=135-139
protocol=tcp
add action=drop chain=virus comment="Drop Messenger Worm" dst-port=135-139
protocol=udp
add action=drop chain=virus comment="Drop Blaster Worm" dst-port=445
protocol=tcp
add action=drop chain=virus comment="Drop Blaster Worm" dst-port=445
protocol=udp
add action=drop chain=virus comment=________ dst-port=593 protocol=tcp
add action=drop chain=virus comment=________ dst-port=1024-1030 protocol=tcp
add action=drop chain=virus comment="Drop MyDoom" dst-port=1080 protocol=tcp
add action=drop chain=virus comment=________ dst-port=1214 protocol=tcp
add action=drop chain=virus comment="ndm requester" dst-port=1363 protocol=
tcp
add action=drop chain=virus comment="ndm server" dst-port=1364 protocol=tcp
add action=drop chain=virus comment="screen cast" dst-port=1368 protocol=tcp
add action=drop chain=virus comment=hromgrafx dst-port=1373 protocol=tcp
add action=drop chain=virus comment=cichlid dst-port=1377 protocol=tcp
add action=drop chain=virus comment=Worm dst-port=1433-1434 protocol=tcp
add action=drop chain=virus comment="Bagle Virus" dst-port=2745 protocol=tcp
add action=drop chain=virus comment="Drop Dumaru.Y" dst-port=2283 protocol=
tcp
add action=drop chain=virus comment="Drop Beagle" dst-port=2535 protocol=tcp
add action=drop chain=virus comment="Drop Beagle.C-K" dst-port=2745 protocol=
tcp
add action=drop chain=virus comment="Drop MyDoom" dst-port=3127-3128
protocol=tcp
add action=drop chain=virus comment="Drop Backdoor OptixPro" dst-port=3410
protocol=tcp
add action=drop chain=virus comment=Worm dst-port=4444 protocol=tcp
add action=drop chain=virus comment=Worm dst-port=4444 protocol=udp
add action=drop chain=virus comment="Drop Sasser" dst-port=5554 protocol=tcp
add action=drop chain=virus comment="Drop Beagle.B" dst-port=8866 protocol=
tcp
add action=drop chain=virus comment="Drop Dabber.A-B" dst-port=9898 protocol=
tcp
add action=drop chain=virus comment="Drop Dumaru.Y" dst-port=10000 protocol=
tcp
add action=drop chain=virus comment="Drop MyDoom.B" dst-port=10080 protocol=
tcp
add action=drop chain=virus comment="Drop NetBus" dst-port=12345 protocol=tcp
add action=drop chain=virus comment="Drop Kuang2" dst-port=17300 protocol=tcp
add action=drop chain=virus comment="Drop SubSeven" dst-port=27374 protocol=
tcp
add action=drop chain=virus comment="Drop PhatBot, Agobot, Gaobot" dst-port=
65506 protocol=tcp
add action=jump chain=forward comment="jump to the virus chain" jump-target=
virusFilter rules of load balancer router.
apr/25/2014 11:03:07 by RouterOS 6.7
software id = R9AG-SV1U
/ip firewall filter
add action=drop chain=forward comment="ISP Router Block" dst-address=
192.168.0.1 in-interface=ether5-LAN
add action=drop chain=forward comment="Drop Invalid Connections"
connection-state=invalid
add action=drop chain=forward comment="ICMP Flood Atack" packet-size=
128-65535 protocol=icmp
add action=drop chain=input comment="DNS Atack" dst-port=53 protocol=udp
add chain=input dst-port=1723 protocol=tcp
add chain=input protocol=gre
add chain=input comment="Established Connections" connection-state=
established
add chain=input comment="Related Connections" connection-state=related
add action=jump chain=forward comment="SYN Flood protect" connection-state=
new jump-target=SYN-Protect protocol=tcp tcp-flags=syn
add chain=SYN-Protect connection-state=new limit=400,5 protocol=tcp
tcp-flags=syn
add action=drop chain=SYN-Protect connection-state=new protocol=tcp
tcp-flags=syn
