OpenVPN n'arrête pas de planter

Oct 20 21:00:44 sb1 openvpn[2082]: <MY_IP>:28523 [vpntest] Peer Connection Initiated with [AF_INET]<MY_IP>:28523
Oct 20 21:00:44 sb1 openvpn[2082]: vpntest/<MY_IP>:28523 MULTI_sva: pool returned  IPv4=10.8.0.6, IPv6=(Not enabled)
Oct 20 21:00:44 sb1 openvpn[2082]: <MY_IP>:28522 WARNING: 'link-mtu' is used inconsistently, local='link-mtu 1576', remote='link-mtu 1376'
Oct 20 21:00:44 sb1 openvpn[2082]: <MY_IP>:28522 WARNING: 'tun-mtu' is used inconsistently, local='tun-mtu 1532', remote='tun-mtu 1332'
Oct 20 21:00:45 sb1 openvpn[2082]: <MY_IP>:28522 [vpntest2] Peer Connection Initiated with [AF_INET]<MY_IP>:28522
Oct 20 21:00:45 sb1 openvpn[2082]: vpntest2/<MY_IP>:28522 MULTI_sva: pool returned IPv4=10.8.0.10, IPv6=(Not enabled)
Oct 20 21:00:46 sb1 openvpn[2082]: vpntest/<MY_IP>:28523 send_push_reply(): safe_cap=940

Fichier client :

client
dev tun
proto tcp
remote <IP> 443
resolv-retry infinite
nobind
tun-mtu 1500
tun-mtu-extra 32
mssfix 1410
persist-key
persist-tun
auth-user-pass
comp-lzo

SERVEUR :

port 443 #- port
proto tcp #- protocol
dev tun
tun-mtu 1500
tun-mtu-extra 32
reneg-sec 0
#mtu-disc yes
mssfix 1410
ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
key /etc/openvpn/easy-rsa/2.0/keys/server.key
dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem
plugin /etc/openvpn/openvpn-auth-pam.so /etc/pam.d/login
#plugin /usr/share/openvpn/plugin/lib/openvpn-auth-pam.so /etc/pam.d/login #- Comment this line if you are using FreeRADIUS
#plugin /etc/openvpn/radiusplugin.so /etc/openvpn/radiusplugin.cnf #- Uncomment this line if you are using FreeRADIUS
client-to-client
client-cert-not-required
username-as-common-name
server 10.8.0.0 255.255.255.0
push "redirect-gateway def1"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 3 30
comp-lzo
persist-key
persist-tun

Qu'est-ce qui fait que le VPN ne cesse d'interrompre la connexion puis de se reconnecter ?

Tous les paramètres MTU sont à 1500. D'où viennent les problèmes de MTU ?