SSTP client dial on demand problem

I have a problem with the SSTP VPN client dial on demand.
When dial on demand is switched off, it works normally but when I enable dial on demand and it should connect (dial), it connects and disconnects and so on…
Tested on RB2011 and RB532 ROS 6.30.4

Config (RB532):

/interface sstp-client
add authentication=mschap2 connect-to=a.b.c.d dial-on-demand=yes \
    disabled=no keepalive-timeout=disabled name=VPN password=yyy pfs=yes \
    profile=encryption-limit user=xxx \
    verify-server-address-from-certificate=no
    
/ppp profile
add idle-timeout=1m name=encryption-limit session-timeout=1d use-compression=\
    no use-encryption=required

Log with dial on demand enabled:

12:22:12 sstp,ppp,info VPN: initializing... 
12:22:12 sstp,ppp,debug VPN: IPCP demandUp 
12:22:12 sstp,ppp,debug VPN: MPLSCP demandUp 
12:22:12 sstp,ppp,info VPN: waiting for packets... 
12:24:37 sstp,ppp,info VPN: connecting... 
12:24:40 sstp,packet VPN sending 
12:24:40 sstp,packet SSTP_DUPLEX_POST /sra_{BA195980-CD49-458b-9E23-C84EE0ADCD75}/ HTTP/1.1\r 
12:24:40 sstp,packet Content-Length: 18446744073709551615\r 
12:24:40 sstp,packet Host: 0.0.0.0\r 
12:24:40 sstp,packet \r 
12:24:40 sstp,packet 
12:24:40 sstp,packet VPN recv 
12:24:40 sstp,packet HTTP/1.1 200 OK\r 
12:24:40 sstp,packet Content-Length: 18446744073709551615\r 
12:24:40 sstp,packet Date: Fri, 04 Sep 2015 10:24:40 GMT\r 
12:24:40 sstp,packet Server: Microsoft-HTTPAPI/2.0\r 
12:24:40 sstp,packet \r 
12:24:40 sstp,packet 
12:24:40 sstp,packet VPN sent control packet type: connect request 
12:24:40 sstp,packet 10 01 00 0e 00 01 00 01 00 01 00 06 00 01  
12:24:40 sstp,packet VPN recv control packet type: connect ack 
12:24:40 sstp,packet 10 01 00 30 00 02 00 01 00 04 00 28 00 00 00 02  
12:24:40 sstp,packet 6e 69 29 30 6f d0 9e e4 dc 85 c7 a4 e5 55 03 24  
12:24:40 sstp,packet 31 98 ef 55 da f2 9b 35 6d b9 63 02 04 65 35 2d  
12:24:40 sstp,ppp,debug VPN: LCP lowerup 
12:24:40 sstp,ppp,debug VPN: LCP open 
12:24:40 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x1 
12:24:40 sstp,ppp,debug,packet    <magic 0x20fa3f76> 
12:24:40 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x0 
12:24:40 sstp,ppp,debug,packet    <auth pap> 
12:24:40 sstp,ppp,debug,packet  VPN: sent LCP ConfRej id=0x0 
12:24:40 sstp,ppp,debug,packet    <auth pap> 
12:24:40 sstp,ppp,debug,packet  VPN: rcvd LCP ConfRej id=0x1 
12:24:40 sstp,ppp,debug,packet    <magic 0x20fa3f76> 
12:24:40 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x2 
12:24:40 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x1 
12:24:40 sstp,ppp,debug,packet    <auth  mschap2> 
12:24:40 sstp,ppp,debug,packet  VPN: sent LCP ConfAck id=0x1 
12:24:40 sstp,ppp,debug,packet    <auth  mschap2> 
12:24:40 sstp,ppp,debug,packet  VPN: rcvd LCP TermReq id=0x2 
12:24:40 sstp,ppp,debug,packet  VPN: sent LCP TermAck id=0x2 
12:24:40 sstp,ppp,debug VPN: LCP lowerdown 
12:24:40 sstp,ppp,info VPN: terminating... 
12:24:40 sstp,ppp,debug VPN: LCP lowerdown 
12:24:40 sstp,ppp,debug VPN: LCP down event in starting state 
12:24:40 sstp,ppp,info VPN: disconnected 
12:24:40 sstp,ppp,info VPN: initializing... 
12:24:40 sstp,ppp,debug VPN: IPCP demandUp 
12:24:40 sstp,ppp,debug VPN: MPLSCP demandUp 
12:24:40 sstp,ppp,info VPN: waiting for packets... 
12:24:47 sstp,ppp,info VPN: connecting... 
12:24:48 sstp,packet VPN sending 
12:24:48 sstp,packet SSTP_DUPLEX_POST /sra_{BA195980-CD49-458b-9E23-C84EE0ADCD75}/ HTTP/1.1\r 
12:24:48 sstp,packet Content-Length: 18446744073709551615\r 
12:24:48 sstp,packet Host: 0.0.0.0\r 
12:24:48 sstp,packet \r 
12:24:48 sstp,packet 
12:24:48 sstp,packet VPN recv 
12:24:48 sstp,packet HTTP/1.1 200 OK\r 
12:24:48 sstp,packet Content-Length: 18446744073709551615\r 
12:24:48 sstp,packet Date: Fri, 04 Sep 2015 10:24:48 GMT\r 
12:24:48 sstp,packet Server: Microsoft-HTTPAPI/2.0\r 
12:24:48 sstp,packet \r 
12:24:48 sstp,packet 
12:24:48 sstp,packet VPN sent control packet type: connect request 
12:24:48 sstp,packet 10 01 00 0e 00 01 00 01 00 01 00 06 00 01  
12:24:48 sstp,packet VPN recv control packet type: connect ack 
12:24:48 sstp,packet 10 01 00 30 00 02 00 01 00 04 00 28 00 00 00 02  
12:24:48 sstp,packet 2e 42 2a a4 25 08 e6 9f 14 5a 3d a4 8f 81 7d 5e  
12:24:48 sstp,packet a2 8b 23 6f 09 82 7a 3a 6c 4e 3a d0 94 7b 1d e2  
12:24:48 sstp,ppp,debug VPN: LCP lowerup 
12:24:48 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x3 
12:24:48 sstp,ppp,debug,packet    <magic 0xb9388c5> 
12:24:48 sstp,ppp,debug VPN: LCP open 
12:24:48 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x0 
12:24:48 sstp,ppp,debug,packet    <auth pap> 
12:24:48 sstp,ppp,debug,packet  VPN: sent LCP ConfRej id=0x0 
12:24:48 sstp,ppp,debug,packet    <auth pap> 
12:24:48 sstp,ppp,debug,packet  VPN: rcvd LCP ConfRej id=0x3 
12:24:48 sstp,ppp,debug,packet    <magic 0xb9388c5> 
12:24:48 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x4 
12:24:48 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x1 
12:24:48 sstp,ppp,debug,packet    <auth  mschap2> 
12:24:48 sstp,ppp,debug,packet  VPN: sent LCP ConfAck id=0x1 
12:24:48 sstp,ppp,debug,packet    <auth  mschap2> 
12:24:48 sstp,ppp,debug,packet  VPN: rcvd LCP TermReq id=0x2 
12:24:48 sstp,ppp,debug,packet  VPN: sent LCP TermAck id=0x2 
12:24:48 sstp,ppp,debug VPN: LCP lowerdown 
12:24:48 sstp,ppp,info VPN: terminating... 
12:24:48 sstp,ppp,debug VPN: LCP lowerdown 
12:24:48 sstp,ppp,debug VPN: LCP down event in starting state 
12:24:48 sstp,ppp,info VPN: disconnected 
12:24:48 sstp,ppp,info VPN: initializing... 
12:24:48 sstp,ppp,debug VPN: IPCP demandUp 
12:24:48 sstp,ppp,debug VPN: MPLSCP demandUp 
12:24:48 sstp,ppp,info VPN: waiting for packets... 
12:24:58 sstp,ppp,info VPN: connecting... 
12:24:58 sstp,packet VPN sending 
12:24:58 sstp,packet SSTP_DUPLEX_POST /sra_{BA195980-CD49-458b-9E23-C84EE0ADCD75}/ HTTP/1.1\r 
12:24:58 sstp,packet Content-Length: 18446744073709551615\r 
12:24:58 sstp,packet Host: 0.0.0.0\r 
12:24:58 sstp,packet \r 
12:24:58 sstp,packet 
12:24:58 sstp,packet VPN recv 
12:24:58 sstp,packet HTTP/1.1 200 OK\r 
12:24:58 sstp,packet Content-Length: 18446744073709551615\r 
12:24:58 sstp,packet Date: Fri, 04 Sep 2015 10:24:58 GMT\r 
12:24:58 sstp,packet Server: Microsoft-HTTPAPI/2.0\r 
12:24:58 sstp,packet \r 
12:24:58 sstp,packet 
12:24:58 sstp,packet VPN sent control packet type: connect request 
12:24:58 sstp,packet 10 01 00 0e 00 01 00 01 00 01 00 06 00 01  
12:24:58 sstp,packet VPN recv control packet type: connect ack 
12:24:58 sstp,packet 10 01 00 30 00 02 00 01 00 04 00 28 00 00 00 02  
12:24:58 sstp,packet 24 09 13 47 fe af 61 9f f5 70 71 79 cb b6 c3 2d  
12:24:58 sstp,packet 2b a6 18 2b 27 54 af 66 0c 62 81 81 74 6d 9e 7e  
12:24:58 sstp,ppp,debug VPN: LCP lowerup 
12:24:58 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x5 
12:24:58 sstp,ppp,debug,packet    <magic 0x308838bd> 
12:24:58 sstp,ppp,debug VPN: LCP open 
12:24:58 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x0 
12:24:58 sstp,ppp,debug,packet    <auth pap> 
12:24:58 sstp,ppp,debug,packet  VPN: sent LCP ConfRej id=0x0 
12:24:58 sstp,ppp,debug,packet    <auth pap> 
12:24:58 sstp,ppp,debug,packet  VPN: rcvd LCP ConfRej id=0x5 
12:24:58 sstp,ppp,debug,packet    <magic 0x308838bd> 
12:24:58 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x6 
12:24:58 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x1 
12:24:58 sstp,ppp,debug,packet    <auth  mschap2> 
12:24:58 sstp,ppp,debug,packet  VPN: sent LCP ConfAck id=0x1 
12:24:58 sstp,ppp,debug,packet    <auth  mschap2> 
12:24:58 sstp,ppp,debug,packet  VPN: rcvd LCP TermReq id=0x2 
12:24:58 sstp,ppp,debug,packet  VPN: sent LCP TermAck id=0x2 
12:24:58 sstp,ppp,debug VPN: LCP lowerdown 
12:24:58 sstp,ppp,info VPN: terminating... 
12:24:58 sstp,ppp,debug VPN: LCP lowerdown 
12:24:58 sstp,ppp,debug VPN: LCP down event in starting state 
12:24:58 sstp,ppp,info VPN: disconnected 
12:24:59 sstp,ppp,info VPN: initializing... 
12:24:59 sstp,ppp,debug VPN: IPCP demandUp 
12:24:59 sstp,ppp,debug VPN: MPLSCP demandUp 
12:24:59 sstp,ppp,info VPN: waiting for packets...

Log with dial on demand disabled for comparison:

12:28:12 sstp,ppp,info VPN: initializing... 
12:28:12 sstp,ppp,info VPN: connecting... 
12:28:14 sstp,packet VPN sending 
12:28:14 sstp,packet SSTP_DUPLEX_POST /sra_{BA195980-CD49-458b-9E23-C84EE0ADCD75}/ HTTP/1.1\r 
12:28:14 sstp,packet Content-Length: 18446744073709551615\r 
12:28:14 sstp,packet Host: 0.0.0.0\r 
12:28:14 sstp,packet \r 
12:28:14 sstp,packet 
12:28:14 sstp,packet VPN recv 
12:28:14 sstp,packet HTTP/1.1 200 OK\r 
12:28:14 sstp,packet Content-Length: 18446744073709551615\r 
12:28:14 sstp,packet Date: Fri, 04 Sep 2015 10:28:43 GMT\r 
12:28:14 sstp,packet Server: Microsoft-HTTPAPI/2.0\r 
12:28:14 sstp,packet \r 
12:28:14 sstp,packet 
12:28:14 sstp,packet VPN sent control packet type: connect request 
12:28:14 sstp,packet 10 01 00 0e 00 01 00 01 00 01 00 06 00 01  
12:28:14 sstp,packet VPN recv control packet type: connect ack 
12:28:14 sstp,packet 10 01 00 30 00 02 00 01 00 04 00 28 00 00 00 02  
12:28:14 sstp,packet f3 1a b6 58 5f 3a 2e 9f 2c d2 21 82 bc f4 ca 52  
12:28:14 sstp,packet 51 fa 1f ea 7d 65 e3 a4 d9 cd 92 70 09 bf d7 a0  
12:28:14 sstp,ppp,debug VPN: LCP lowerup 
12:28:14 sstp,ppp,debug VPN: LCP open 
12:28:14 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x1 
12:28:14 sstp,ppp,debug,packet    <magic 0x985e8c1> 
12:28:15 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x0 
12:28:15 sstp,ppp,debug,packet    <auth pap> 
12:28:15 sstp,ppp,debug,packet  VPN: sent LCP ConfRej id=0x0 
12:28:15 sstp,ppp,debug,packet    <auth pap> 
12:28:15 sstp,ppp,debug,packet  VPN: rcvd LCP ConfRej id=0x1 
12:28:15 sstp,ppp,debug,packet    <magic 0x985e8c1> 
12:28:15 sstp,ppp,debug,packet  VPN: sent LCP ConfReq id=0x2 
12:28:15 sstp,ppp,debug,packet  VPN: rcvd LCP ConfReq id=0x1 
12:28:15 sstp,ppp,debug,packet    <auth  mschap2> 
12:28:15 sstp,ppp,debug,packet  VPN: sent LCP ConfAck id=0x1 
12:28:15 sstp,ppp,debug,packet    <auth  mschap2> 
12:28:15 sstp,ppp,debug,packet  VPN: rcvd LCP ConfAck id=0x2 
12:28:15 sstp,ppp,debug VPN: LCP opened 
12:28:15 sstp,ppp,debug,packet  VPN: rcvd CHAP Challenge id=0x0 
12:28:15 sstp,ppp,debug,packet     <challenge len=16> 
12:28:15 sstp,ppp,debug,packet     <name abcd> 
12:28:15 sstp,ppp,debug,packet  VPN: sent CHAP Response id=0x0 
12:28:15 sstp,ppp,debug,packet     <response len=49> 
12:28:15 sstp,ppp,debug,packet     <name xxx> 
12:28:15 sstp,ppp,debug,packet  VPN: rcvd CHAP Success id=0x0 
12:28:15 sstp,ppp,debug,packet     S=DD5DB5EF7CC1D61E9D636862A68FF6D9370A9601 
12:28:15 sstp,ppp,info VPN: authenticated 
12:28:15 sstp,packet VPN sent control packet type: connected 
12:28:15 sstp,packet 10 01 00 70 00 04 00 01 00 03 00 68 00 00 00 02  
12:28:15 sstp,packet f3 1a b6 58 5f 3a 2e 9f 2c d2 21 82 bc f4 ca 52  
12:28:15 sstp,packet 51 fa 1f ea 7d 65 e3 a4 d9 cd 92 70 09 bf d7 a0  
12:28:15 sstp,packet 23 e6 c1 99 ca f4 d6 e0 65 f9 3c cb 54 12 5c 16  
12:28:15 sstp,packet cb ae 77 9e 09 95 fe cd 65 b3 96 b4 c9 a7 f5 a6  
12:28:15 sstp,packet 2f f3 49 a5 71 d6 48 2c 32 7c 4b 09 62 1c 0a 13  
12:28:15 sstp,packet 43 c9 fe 8a 16 e4 72 b2 94 9d 56 30 f2 82 da 7f  
12:28:15 sstp,ppp,debug VPN: IPCP lowerup 
12:28:15 sstp,ppp,debug VPN: IPCP open 
12:28:15 sstp,ppp,debug,packet  VPN: sent IPCP ConfReq id=0x1 
12:28:15 sstp,ppp,debug,packet     <addr 0.0.0.0> 
12:28:15 sstp,ppp,debug VPN: IPV6CP open 
12:28:15 sstp,ppp,debug VPN: MPLSCP lowerup 
12:28:15 sstp,ppp,debug VPN: MPLSCP open 
12:28:15 sstp,ppp,debug,packet  VPN: sent MPLSCP ConfReq id=0x1 
12:28:15 sstp,ppp,debug VPN: BCP open 
12:28:15 sstp,ppp,debug VPN: CCP lowerup 
12:28:15 sstp,ppp,debug VPN: CCP open 
12:28:15 sstp,packet VPN recv control packet type: echo request 
12:28:15 sstp,packet 10 01 00 08 00 08 00 00  
12:28:15 sstp,packet VPN sent control packet type: echo response 
12:28:15 sstp,packet 10 01 00 08 00 09 00 00

Any ideas what is wrong with my config?
Or is it a ROS bug?