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Any help would be appreciated. Our issue is that we have two offices that are 100 miles apart. We have a 60 x 4 cable internet connection at each site with static IP addresses. each location also now has a TL-ER6020 router connected to the provider's cable-modem. We have established a VPN Tunnel between the locations. We want to use this VPN tunnel to carry voice-calls between our two offices.

The problem is that we can make a call but after a period of time, we lose the audio and the call fails. I am struggling to isolate whether the problem is in one of my routers, or is with the cable provider. I felt that the cable provider was having issues but they argue that their equipment is working perfectly. When I plug my laptop into the ER6020 I can get onto the internet fine. when I use command-line to try to ping and send icmp data across the Vpn, I get inconsistent results. Specifically, if I my local router is assigned as gateway 192.168.0.1 and the far end router is 192.168.1.1, I run the following command: ping 192.168.1.1 -n 30 the test might succeed for the first 6 - 10 tries, and then I receive "destination host unreachable" for the next 5 - 10, and so it goes with spurts of data succeeding and then brief periods of failure. The total packet loss seems to continually run at 30 -40% lost. I am able to ping other addresses successfully 100% of the time though. For instance, I ping google DNS (ping 8.8.8.8) and receive 100% success.

Can someone help me go a level deeper to understand if the trouble is because of my equipment, or out in the internet on the cable-company's backbone, etc?

Thank you.