When I try to access certain websites they will not load. For example www.google.com loads fine but www.yahoo.com will not. This happens on many websites I try and access. I updated the firmware on my Mikrotik RB201 1UiAS-RM but still have the same problem. This happens on wifi and hardware connection. Please help!
I would start by checking out MTU.
Do you have a suggestion on what the MTU should be set at?
The definitive answer will come from your ISP, but generally speaking, 1500 if the service is delivered over ethernet, 1492 if it’s coming over DSL. Also, blocking ICMP will prevent Path MTU Discovery from working and PMTUD can be helpful.
Please do a /export of your configuration and post it.
As written, when you block all ICMP this is a common problem. Don’t do that, not even when bloggers/“experts” recommend it.
You can work around such damage (e.g. when others already made it and you cannot change it) using a mangle rule to reduce
the MSS of your TCP connections. Like this:
/ip firewall mangle
add action=change-mss chain=forward new-mss=clamp-to-pmtu passthrough=yes \
protocol=tcp tcp-flags=syn
I recommend to always include this rule when you have any interface with an MTU less than 1500
(e.g. when you have PPPoE towards the ISP or when you are using a VPN)
What DNS server do you use?