Getting yellow triangle over network icon. Some sites load, some don't

C:\Windows\system32>ping facebook.com -f -l 1423

Pinging facebook.com [69.171.229.11] with 1423 bytes of data:
Reply from 69.171.229.11: bytes=1423 time=329ms TTL=241
Reply from 69.171.229.11: bytes=1423 time=260ms TTL=241
Reply from 69.171.229.11: bytes=1423 time=222ms TTL=241
Reply from 69.171.229.11: bytes=1423 time=210ms TTL=241

Ping statistics for 69.171.229.11:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 210ms, Maximum = 329ms, Average = 255ms

That looks a good reply did you set the mtu to 1451 as that would be the correct setting for the computer i would do this and then re-boot pc.

I did, and it didn't work.

When you set the mtu to 1451 you did restart the laptop to complete the re-configuration please confirm?

Also what internet security package are you using(anti-virus and firewall)?

I did restart, yes. Unless I was supposed to do it a specific way?

That is fine Lakenz you did it right no special way.

And the internet security package....

doubled822 - No. D:

TheCyberMan - AVG Free

And firewall...

Windows Firewall