Ну, вообще-то не совсем "не пашет", но глючит безбожно.
А именно - mtr на модем показывает 20-40% потерь, а те пакеты, что доходят, идут 4(!) секунды.
Вот, кстати, пример. Удивляют ровные времена: 4 сек, 3 сек, 2 сек, с точностью до тысячных.
[root@st ~]# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
From 192.168.1.3 icmp_seq=1 Destination Host Unreachable
From 192.168.1.3 icmp_seq=2 Destination Host Unreachable
From 192.168.1.3 icmp_seq=3 Destination Host Unreachable
q64 bytes from 192.168.1.1: icmp_seq=4 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=6 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=7 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=8 ttl=64 time=3826 ms
64 bytes from 192.168.1.1: icmp_seq=9 ttl=64 time=3000 ms
64 bytes from 192.168.1.1: icmp_seq=11 ttl=64 time=2000 ms
64 bytes from 192.168.1.1: icmp_seq=12 ttl=64 time=2001 ms
64 bytes from 192.168.1.1: icmp_seq=13 ttl=64 time=2000 ms
64 bytes from 192.168.1.1: icmp_seq=14 ttl=64 time=3000 ms
64 bytes from 192.168.1.1: icmp_seq=15 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=16 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=17 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=18 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=19 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=20 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=21 ttl=64 time=4000 ms
64 bytes from 192.168.1.1: icmp_seq=23 ttl=64 time=3000 ms
64 bytes from 192.168.1.1: icmp_seq=24 ttl=64 time=3000 ms
64 bytes from 192.168.1.1: icmp_seq=25 ttl=64 time=2838 ms
64 bytes from 192.168.1.1: icmp_seq=26 ttl=64 time=3006 ms
64 bytes from 192.168.1.1: icmp_seq=27 ttl=64 time=3014 ms
64 bytes from 192.168.1.1: icmp_seq=28 ttl=64 time=4031 ms
64 bytes from 192.168.1.1: icmp_seq=29 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=30 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=31 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=32 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=33 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=34 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=35 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=36 ttl=64 time=4032 ms
64 bytes from 192.168.1.1: icmp_seq=37 ttl=64 time=4033 ms
^C
--- 192.168.1.1 ping statistics ---
41 packets transmitted, 32 received, +3 errors, 21% packet loss, time 40109ms
rtt min/avg/max/mdev = 2000.747/3594.589/4033.763/663.139 ms, pipe 5