Can't reach some route in Anyconnect

[Kevin]

Hi list 

There is a thing goes so weird. 

My VPN Server is located in SG. 
OS is Ubuntu 12.04 
Ocserv is 0.3.2 

In the config file, I added about 20 route 

most of them are working well. 
But the tumblr route 66.0.0.0/255.0.0.0 
and twitter Image server route 199.96.0.0/255.255.0.0 can't be reached. 

I can ping them. but can not get HTTP response through the VPN. 
Then I sshed to my server to try wget to get the webpage, and I got it. So my server's IP is not banned. 

I tried reduce the MTU to 1300, 1200 but not helped. 

do you have any idea about this thing? 

Thank you very much. 

--  
Kevin
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