Сталкиваюсь с аналогичной проблемой.
Клиенты жалуются на разрывы. В пике ~800 сессий.
top - 11:26:26 up 21 days, 23:32, 2 users, load average: 0.04, 0.03, 0.00
Tasks: 1187 total, 1 running, 1186 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.2%us, 0.3%sy, 0.0%ni, 95.2%id, 0.0%wa, 0.3%hi, 4.1%si, 0.0%st
Mem: 16633452k total, 1176980k used, 15456472k free, 159404k buffers
Swap: 8388600k total, 0k used, 8388600k free, 508496k cached
accel-pptpd v0.8.4 compiled for pppd-2.4.4, linux-2.6.24.6
аналогично в логах:
Mar 25 07:50:52 vpn pptp[18655]: No response to 30 echo-requests
Mar 25 08:00:24 vpn pptp[18406]: No response to 30 echo-requests
Mar 25 08:28:41 vpn pptp[21275]: No response to 30 echo-requests
Mar 25 08:30:29 vpn pptp[23742]: No response to 30 echo-requests
Mar 25 08:31:14 vpn pptp[22634]: No response to 30 echo-requests
Mar 25 08:42:06 vpn pptp[20187]: No response to 30 echo-requests
Mar 25 08:51:24 vpn pptp[23079]: No response to 30 echo-requests
Mar 25 08:55:52 vpn pptp[25930]: No response to 30 echo-requests
Mar 25 08:57:56 vpn pptp[18818]: No response to 30 echo-requests
Mar 25 09:25:05 vpn pptp[6018]: No response to 30 echo-requests
Mar 25 09:25:20 vpn pptp[19332]: No response to 30 echo-requests
Mar 25 09:28:18 vpn pptp[29291]: No response to 30 echo-requests
Mar 25 09:37:51 vpn pptp[30879]: No response to 30 echo-requests
Mar 25 09:47:01 vpn pptp[31635]: No response to 30 echo-requests
Mar 25 09:49:35 vpn pptp[25555]: No response to 30 echo-requests
Mar 25 09:56:16 vpn pptp[21339]: No response to 30 echo-requests
Mar 25 10:15:12 vpn pptp[11037]: No response to 30 echo-requests