Newbie Questions for a Specific Problem

[Mark Phillips <mark () phillipsmarketing biz>]

I am new to wireshark and network monitoring, so please bear with me. I am
looking for some guidance on how to solve a specific network problem...

The problem
My T-Mobile MYTouch 4G is supposed to be able to make calls over wifi.  It
connects to some wifi hot spots, but not others. In particular, it connects
at a local Stabucks for wifi calls, but now my office wifi network. I need
to find a way to make it work over my office network. The kicker is the
phone says I am connected to wifi at both locations, but just can't make a
phone call using wifi over my office network.  Basically, one enables Wifi,
and the phone scans and connects to a network. This process succeeds in both
locations. There is a second button to enable wifi calling, which fails on
my office network, but not at Starbucks. The error I message when it does
not connect is "Connection Error - ISP or T-Mobile Network Error." T-Mobile
technical support says it is a problem with my network, so I am SOL. But,
they cannot tell me what my network has to do to be compatible with wifi
calling.

I thought I might be able to use wireshark see what happens when the phone
connects at Starbucks and not on my office network, to see if I can change
my network to work with wifi calling. My network setup - Linksys WRT54G
Wireless Router configured as an access point connected to a BEFSX-41
Linksys router, which is connected to my cable modem. I use MAC filtering
and WPA and AES with a pre-shared key for wireless security.

Questions...
1. Is my initial assumption that I can use wireshark to figure out what is
not working with my network and what is working at Starbucks for wifi calls
even feasible? Do I have a chance of figuring out what needs to be changed
on my network to make wifi calling work?

2. Do I need a PhD in LAN Diagnostics to figure out what is happening on my
network versus Starbucks and fix my network?

3. I fired up wireshark on my work network and starting capturing packets on
eth0. I looked at the DHCP routing table in the router and found the phone
was assigned 192.168.25.203. I set a filter for that address (ip ==
192.168.25.203 or eth.addr == f8:db:7f:42:db:75), hit a web page on the
phone and no packets were captured, even though the phone says it was
connected to the wireless network. The page loaded on the phone. Tried
sending/receiving an email. I also tried hitting the "enable wifi calling"
button, and no packets. What am I doing wrong?

Thanks,

Mark

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