Q:

OpenVPN on Android TCP retransmissions after OpenVPN server reboot

I raised OpenVPN on server for the first time.  It worked fine until the server rebooted.  The firewall configuration is unchanged.  When I tcpdump from tun interface on the server, I always get TCP retransmissions on all TCP packets larger than a few bytes in Android. 
Using a similar(read: same) configuration on my Linux box from where I'm posting this message now works just fine; no retransmissions, no loss. 
It did work just fine before the server rebooted.  What could possibly cause this?  I already tried rebooting Android, it didn't help. 
Client configuration, used on both Linux PC and Android tablet:
dev tun
client
remote 192.168.0.1
persist-key
persist-tun
nobind
pkcs12 user.p12
mssfix 1480
cipher AES-256-CBC
verb 3

1480 is below the mtu of uplink connection on server which is 1492. 
I tried adding tun-mtu 1480 to Android but that didn't help either. 

A:

final attempt: i set both 'tun-mtu' and 'mssfix' to 1380 on both server and client.  surprisingly, it worked.