root@debian:~# pppd 10.20.30.100:10.20.30.200 asyncmap 0x11111111 noauth nocrtscts nolock local proxyarp noccp noaccomp nopcomp ms-dns 212.24.188.130 ms-dns 212.24.188.131 debug /dev/ttyUSB0
Mar 19 20:55:11 debian pppd[24714]: pppd 2.4.6 started by user, uid 0
Mar 19 20:55:11 debian pppd[24714]: using channel 13
Mar 19 20:55:11 debian pppd[24714]: Using interface ppp0
Mar 19 20:55:11 debian pppd[24714]: Connect: ppp0 <--> /dev/ttyUSB0
Mar 19 20:55:11 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:11 debian kernel: usb 2-1.4: ark3116: don't know how to do software flow control
Mar 19 20:55:14 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:17 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:20 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:23 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:26 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:29 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:32 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:35 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:38 debian pppd[24714]: sent [LCP ConfReq id=0x1 ]
Mar 19 20:55:41 debian pppd[24714]: LCP: timeout sending Config-Requests
Mar 19 20:55:41 debian pppd[24714]: Connection terminated.
Mar 19 20:55:41 debian pppd[24714]: Modem hangup
Mar 19 20:55:41 debian pppd[24714]: Exit.
Mar 19 20:55:41 debian kernel: usb 2-1.4: ark3116: don't know how to do software flow control
root@switch:/# pppd debug asyncmap 0x11111111 /dev/ttyS0
Sat Mar 19 21:48:28 2016 daemon.notice pppd[1226]: pppd 2.4.7 started by root, uid 0
Sat Mar 19 21:48:28 2016 daemon.debug pppd[1226]: using channel 14
Sat Mar 19 21:48:28 2016 daemon.info pppd[1226]: Using interface ppp0
Sat Mar 19 21:48:28 2016 daemon.notice pppd[1226]: Connect: ppp0 <--> /dev/ttyS0
Sat Mar 19 21:48:28 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:31 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:34 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:37 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:40 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:43 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:46 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:49 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:52 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:55 2016 daemon.debug pppd[1226]: sent [LCP ConfReq id=0x1 ]
Sat Mar 19 21:48:58 2016 daemon.warn pppd[1226]: LCP: timeout sending Config-Requests
Sat Mar 19 21:48:58 2016 daemon.notice pppd[1226]: Connection terminated.
Sat Mar 19 21:48:58 2016 daemon.notice pppd[1226]: Modem hangup
Sat Mar 19 21:48:58 2016 daemon.info pppd[1226]: Exit.
Nincsenek rcvd üzenetek.
Ugyanez (asyncmap nélkül), egy másik routerrel, amin Backfire van és a ttyS0-ról csatlakozik rá a számítógép, simán működik.
Megj.: az órák rosszul járnak...