PPTP VPN "Protocol-Reject for unsupported protocol" and connection failure

hey,
i have set a PPTP VPN and i'm able to connect with about 40 cellular routers properly, except two problems:

1. 1 - at some point after i'm already connected to the VPN, i randomly get these "Protocol-Reject for unsupported protocol" messages:
   
   
   Code:

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   Jun 13 17:51:52 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0xf6aa
Jun 13 17:51:52 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x2864
Jun 13 17:51:52 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x5
Jun 13 17:51:52 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 'NTCITS IPI' (0xc1)
Jun 13 17:51:53 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x85
Jun 13 17:51:53 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x215
Jun 13 17:51:53 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 'KNX Bridging Data' (0x51)
Jun 13 17:51:53 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0xe1
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0xde74
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x7e62
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0xf
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 'Stream Protocol ST-II' (0x33)
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 'SNA over 802.2' (0x4b)
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x1c7e
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x93
Jun 13 17:51:54 linux-zipx pppd[21565]: Protocol-Reject for unsupported protocol 0x5eba

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   at this point i can't do anything and only a reconnect to the VPN fixes this problem.
   
   if happens in a much higher rate when i connect the VPN through my linux machine (opensuse 12.1), usually a few minutes after i start applications that use a lot of bandwidth, KTorrent for example.
   
2. 2 - sometimes the routers aren't able to connect to the VPN. i get the following messages in the routers:
   
   
   Code:

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   info        Jun 13 23:18:10        syswatcher[1]        start service [pptp.ADTV_PPTP]
notice        Jun 13 23:18:10        pppd[1787]        Connection terminated.
notice        Jun 13 23:18:10        pptp[1788]        anon log[pptp_read_some:pptp_ctrl.c:544]: read returned zero, peer has closed
notice        Jun 13 23:18:10        pptp[1788]        anon log[call_callback:pptp_callmgr.c:79]: Closing connection (call state)
notice        Jun 13 23:18:10        pptp[1812]        anon log[main:pptp.c:320]: The synchronous pptp option is NOT activated
notice        Jun 13 23:18:10        pptp[1814]        anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 1 'Start-Control-Connection-Request'
notice        Jun 13 23:18:10        pptp[1814]        anon log[ctrlp_disp:pptp_ctrl.c:739]: Received Start Control Connection Reply
notice        Jun 13 23:18:10        pptp[1814]        anon log[ctrlp_disp:pptp_ctrl.c:773]: Client connection established.
info        Jun 13 23:18:11        pppd[1787]        set exit timer
info        Jun 13 23:18:11        pppd[1787]        Exit.
notice        Jun 13 23:18:16        pptp[1814]        anon log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request'
notice        Jun 13 23:18:16        pptp[1814]        anon log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
notice        Jun 13 23:18:16        pptp[1814]        anon log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 0, peer's call ID 22528).
notice        Jun 13 23:18:16        pppd[1813]        pppd 2.4.4 started by root, uid 0
info        Jun 13 23:18:16        pppd[1813]        Using interface ppp1
notice        Jun 13 23:18:16        pppd[1813]        Connect: ppp1 <--> /dev/pts/3

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   and i get these messages in astaro's pptpd log:
   
   Code:

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   2012:06:13-23:42:10 fw pptpd[25681]: GRE: accepting packet #1144
2012:06:13-23:42:10 fw pptpd[25582]: MGR: Reaped child 29033
2012:06:13-23:42:10 fw pptpd[29033]: GRE: read(fd=6,buffer=805a540,len=8196) from PTY failed: status = -1 error = Input/output error, usually caused by unexpected termination of pppd, check option syntax and pppd logs
2012:06:13-23:42:10 fw pptpd[29033]: CTRL: PTY read or GRE write failed (pty,gre)=(6,7)
2012:06:13-23:42:10 fw pptpd[29033]: CTRL: Reaping child PPP[29035]
2012:06:13-23:42:10 fw pptpd[29033]: CTRL: Client 188.64.202.34 control connection finished
2012:06:13-23:42:10 fw pptpd[29033]: CTRL: Exiting now
2012:06:13-23:42:10 fw pppd-pptp[29035]: LCP: timeout sending Config-Requests
2012:06:13-23:42:10 fw pppd-pptp[29035]: Connection terminated.
2012:06:13-23:42:10 fw pppd-pptp[29035]: Modem hangup
2012:06:13-23:42:10 fw pppd-pptp[29035]: Exit.

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   the only way to fix this problem is to disable the vpn connection in the router for about 10-15, the enable it again.

is anybody familiar with these problems or might know how to fix them?

any help would be much appreciated! ;)