Traffic on port 53 fails on LTE but works on WiFi

Quan Zhou quanzhou822 at
Mon Nov 19 05:26:49 CET 2018

> 1) What can I try on the server peer side to diagnose?

# tcpdump udp port 53

maybe you can try to `ping` and `traceroute` to your server in addition.

On 11/19/18, John <graysky at> wrote:
> I have a simple WireGuard VPN setup I use running WG on a home Linux
> box and connecting to it with several iOS clients.  The server peer is
> setup on port 53 since a the networkadmins of some remote WiFi
> networks my mobile devices seems to block udp traffic on higher ports.
> Encrypted connections work fine on WiFi as I have setup, but do _not_
> work when I connect via LTE (Verizon supplying the data).  On LTE, I
> am no longer able to transfer data to/from the server peer but I can
> handshake with it.
> If I inspect the output of `sudo wg` on the server peer, I see the
> endpoint IP address changes to reflect my Verizon LTE IP and the time
> since the last handshake reset to a few seconds which is consistent
> with my ability to connect to the WireGuard peer server.
> I am unable to transfer data (pull up a web site or check email etc).
> It's as/if Verizon is blocking my data flow on port 53.  If I change
> the port from 53 to 123, it seems to work fine although I do not have
> universal connectivity on the various WiFi networks I visit on port
> 123.  The optimal port would be 53 for my use case.
> So the questions:
> 1) What can I try on the server peer side to diagnose?
> 2) Do people feel that Verizon is actively blocking the connection on port
> 53?
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Quan Zhou

quanzhou822 at

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