I've exhausted my troubleshooting abilities on an issue and looking for some advice moving forward.
First, I'm thinking this is either an issue with my ISP (Comcast Business) or my new modem (ARRIS SB6190) or both. I've happily run OpenWrt on a NetGear WNDR3700v2 for 3 or 4 years behind a Motorola SB6141 modem. I have raspbx running on a raspberry pi for about a year and this was all fine until a few months ago. I began getting latency spikes and packet loss confirmed by MTR. I ended up buying a new modem (the SB6190) and that problem seemed gone. Shortly after, I upgraded OpenWrt from 15.01? to the current version 15.05, choosing to keep the settings. All seems swell.
A few days after the upgrades, I can't make outgoing calls. Never had this trouble before and haven't changed any firewall settings. I restarted asterisk, checked firewall settings, SIP settings and even went back and forth with my VOIP provider (Vitelity). Though incoming traffic works fine and SIP registration works fine, Vitelity said they saw no traffic from me when I made outgoing calls. I logged onto my router and performed tcpdump and could clearly see the packets (UDP) being sent, but no return packets (huh???). I reset the WAN interface on OpenWrt and even restarted the router, but it did not help.
What did and still does work? Restarting the modem. When I restart the modem, I'm able to initiate SIP calls (UDP connections to Vitelity's SIP server) for a few days (2-5), after which they begin to fail. I've found no other network issues at all. I spend most of the day with persistent SSH and VPN (IPSEC and SSL) connections that work just fine, not to mention the gobs of web traffic and netflix streaming.
I guess I could buy a different modem and try that, but how could a modem malfunction in this very specific way? Any advice on how to figure this out would be appreciated. In the meantime, I'm cycling my modem every few days.
Thanks.