[Inquiry] Detecting Dropped Packets

Technical Support for Routers
1

Greetings,

TL;DR:
Can anyone guide me how to detect/trace dropped packets > across all active connections
on the router?

My question is, how can I trace/detect dropped packets and where they drop using an GL iNet router, specifically, AR750 on latest 3.026.

The scenario is as follows:
My ISP has major restriction on VOIP, almost all online games using voice chat, voice chat doesn’t work.

What I want to do is:

  1. Detect/Trace where packets drop, which would most probably be due to the ISP major restriction.
  2. Recognize the server/ip/domain where packets drop.
  3. Add that server/ip/domain as a VPN Policy to only run VPN on it.

Kindly note that:
When I run the VPN on my PC’s MAC Address, Voice Chat and every restricted service runs totally fine. Therefore, such restrictions are 100% because of the ISP.

2

If it’s your ISP problem, your data packets won’t necessarily be rejected or dropped on the AR750

3

I don’t mean that the AR750 is the cause of the dropped packets. I’m asking how I can actually trace the route of the dropped packets and figure out when they get rejected.

4

Sorry, I have no experience in this field, so I cannot provide you with useful help information

5

tcpdump is a standard tool for “looking at” packets. It can be installed with the tcpdup-mini package. I usually use tcpdump -ni <some interface> <selector for the packets I'm looking for> to see if the packets are coming into the router and leaving it. As a guess, something like

I haven’t tried to log firewall “drops” using the standard iptables tooling. Knowing if the packets are flowing as expected, or where they “disappear” is often enough to point to an “error” in those rules.