OpenVPN not showing several sites

[GoogleCodeExporter]

Firmware RT-N56U_3.4.3.6-069_base

Before this build I've used OpenVPN server via entware on my flash drive 
(worked perfectly, but low speed).

After installation of the last firmware I've tried to configure the new 
built-in OpenVPN server using my certs and keys (putted to the router using 
WinSCP) from the flash drive (correct me if that was wrong).

No matter what to change on the router's OpenVPN config page, I have a problem. 
Here are the steps:
1. Connection from my office Ubuntu machine to the router is fast and OK.
2. When I try to access some sites (Google search, GMail, YouTube etc.), their 
pages are infinitely loading or I got an error ERR_EMPTY_RESPONSE
3. VK.com, tumblr, Yandex start page are working, but Search and NEWS.yandex.ru 
— not, also Twitter and Facebook are not working too.

Server config (from router's page):

Encapsulation Layer: TUN
Transport: UDP
Port: 1194
HMAC signature check (tls-auth): No
Route all client's traffic through the VPN: No
Network to use for the tunnel: 10.8.0.0

# Custom user conf file for OpenVPN server
auth none
cipher AES-128-CBC
comp-lzo
max-clients 10
;duplicate-cn
client-to-client
keepalive 10 60
nice 3
verb 0
mute 10

Client config:
client
remote mydomain.myftp.org
ca /home/ubuntu/ca.crt
cert /home/ubuntu/openvpn/keys/client.crt
key /home/ubuntu/openvpn/keys/client.key
cipher AES-128-CBC
comp-lzo yes
dev tun
proto udp
nobind
auth-nocache
script-security 2
persist-key
persist-tun
user openvpn
group openvpn

What should I change? I can't find where is the bug or it's my mistake.

Original issue reported on code.google.com by xnightma...@gmail.com on 1 Oct 2013 at 1:34

[GoogleCodeExporter]

Please, show full config files on both sides.
on router:
cat /etc/openvpn/server/server.conf
and the same way on ubuntu...
There can be some possible reasons. Some things you should check on Ubuntu: 
routes, names resolving service, proxy settings (if there any at the office). 
There can be many other thing to check.
PS: I also use Ubuntu at home and at work. It becomes more and more buggy... 
Sometimes I don't know what to expect from system. I'm gonna change reinstall 
it to RedHat when as soon as I'll have some free time. =/

Original comment by d...@soulblader.com on 7 Oct 2013 at 8:12

[GoogleCodeExporter]

Problem is solved on ixbt forum today: there was an issue, so I should change 
the tun-mtu and fragment parameters in server and client configs. After strict 
defining of this parameters all is working fine.

Original comment by xnightma...@gmail.com on 7 Oct 2013 at 8:35

[GoogleCodeExporter]

Original comment by Dr.Sydorenko.O on 13 Oct 2013 at 1:26

• Changed state: Done