I'm having an issue with calls dropping. I'll be on the phone, hear a click, about a second later I get the dial tone. This doesn't happen on every call but it is happening about 50% of the time. Occasionally we are getting echoing as well where we can hear ourselves talking or the person we are speaking to can hear themselves. I can confirm that it's not the phones as I have POTS service as well and the phones work fine with it. I have made multiple patch cables and bought a few as well with no luck in fixing this issue. We use this in my home office so it's becoming a real problem.

I have a Grandstream HT502 adapter connected to a TP-Link R470T+ Multi-WAN router. It's been assigned a static IP, port range 5004-65000 UDP has been forwarded, SIP ALG has been turned off. I have a multi-wan setup so I was able to test this over different ISPs. The adapter however is not part of my load balancing setup and is set to use only 1 ISP. I have also provisioned the port the adapter is using to have a full 512kbps upload and 1024kbps download minimum at all times.

Any help is greatly appreciated!