Softether SSTP + Mikrotik SSTP = drops

[lex]

Hello, trying to configure mikrotik (MT) as a client for SoftEther SSTP (SE), with no luck.
1) Connection configured and working
2) I can send pings from MT directly without problems

When it comes to clients behind router, however, connection drops, and i see that in SE logs:
[code]
2015-05-07 07:17:25.588 [HUB "DEFAULT"] Session "SID-TEST-24": The session has been terminated. The statistical information is as follows: Total outgoing data size: 65105366 bytes, Total incoming data size: 75291633 bytes.
2015-05-07 07:17:25.618 Connection "CID-72" terminated by the cause "The VPN session has been deleted. It is possible that either the administrator disconnected the session or the connection from the client to the VPN Server has been disconnected." (code 11).
2015-05-07 07:17:25.618 Connection "CID-72" has been terminated.
2015-05-07 07:17:25.618 The connection with the client (IP address 1.1.1., Port number 58272) has been disconnected.
2015-05-07 07:17:26.041 [HUB "DEFAULT"] SecureNAT: The TCP session 759 has been deleted.
2015-05-07 07:17:26.534 [HUB "DEFAULT"] SecureNAT: The TCP session 1033 has been deleted.
2015-05-07 07:17:26.544 [HUB "DEFAULT"] SecureNAT: The UDP session 992 has been deleted.
2015-05-07 07:17:26.635 [HUB "DEFAULT"] SecureNAT: The TCP session 1035 has been deleted.
2015-05-07 07:17:26.816 [HUB "DEFAULT"] SecureNAT: The TCP session 1030 has been deleted.
2015-05-07 07:17:26.816 [HUB "DEFAULT"] SecureNAT: The TCP session 1034 has been deleted.
2015-05-07 07:17:26.917 [HUB "DEFAULT"] SecureNAT: The UDP session 600 has been deleted.
2015-05-07 07:17:31.145 [HUB "DEFAULT"] SecureNAT: The UDP session 995 has been deleted.
2015-05-07 07:17:31.770 [HUB "DEFAULT"] SecureNAT: The UDP session 996 has been deleted.
2015-05-07 07:17:32.344 [HUB "DEFAULT"] SecureNAT: The UDP session 997 has been deleted.
2015-05-07 07:17:36.863 [HUB "DEFAULT"] SecureNAT: The UDP session 1004 has been deleted.
2015-05-07 07:17:38.152 [HUB "DEFAULT"] SecureNAT: The UDP session 979 has been deleted.
2015-05-07 07:17:39.380 [HUB "DEFAULT"] SecureNAT: The TCP session 703 has been deleted.
2015-05-07 07:17:40.658 [HUB "DEFAULT"] SecureNAT: The UDP session 1006 has been deleted.
2015-05-07 07:17:41.957 [HUB "DEFAULT"] SecureNAT: The UDP session 1013 has been deleted.
2015-05-07 07:17:41.957 [HUB "DEFAULT"] SecureNAT: The UDP session 1014 has been deleted.
2015-05-07 07:17:41.987 [HUB "DEFAULT"] SecureNAT: The UDP session 1015 has been deleted.
2015-05-07 07:17:45.751 [HUB "DEFAULT"] SecureNAT: The UDP session 315 has been deleted.
2015-05-07 07:17:47.805 [HUB "DEFAULT"] SecureNAT: The UDP session 1016 has been deleted.
2015-05-07 07:17:50.472 [HUB "DEFAULT"] SecureNAT: The UDP session 1020 has been deleted.
[/code]

Router reconnects, works for few seconds, and drops after that. And all that repeats...

I tried configuring with bridge instead, and now it fails with

[code]
2015-05-07 08:10:01.403 Connection "CID-45" terminated by the cause "The VPN session has been deleted. It is possible that either the administrator disconnected the session or the connection from the client to the VPN Server has been disconnected." (code 11).
[/code]

[lex]

It feels like MTU problem. If i open some particular site, i can refresh it as many times as i want without drops.
However, if i open another site, session immediately crashes.
It can be easily reproduced by me, but i cannot see anything useful in logs :(
This looks very related to http://www.vpnusers.com/viewtopic.php?f=7&t=4447

[a.woll]

Did you try another sstp client like the one in Windows?
Your internet access on client side has a static ip, hasn't it?