So you are connecting in this way right:
Laptop -> Wired ethernet -> Switch (or Access point) ->Etherdongle -> Out of Etherdongle DMX out -> Lynx Express
right?
A few things to check
1. If you are wired to the Switch / Access Point what's your IP Address that's been assigned to the Laptop
It should be 1.192.168.1.XX ( Gateway should be 192.168.1.1)
2. If connecting to a Access Point, have you turned off your wireless and force the Laptop to use the Hardwired Ethernet connection
3. On the Lynx Express, have you got the "Remove for Wireless" jumper set correctly, it should be ON for wired mode?
4. On the Lynx Express have you got the terminate jumper installed?
5. In LSP for the Configure outputs, is it set with the default values, and made active, by setting the check boxes on all the universes
(In LSP if there is a problem with set up after the initial set up and LSP can't "see" the Ether dongle, it will Un-check the Configure outputs by default even though you thought you set them up correctly the first time)
6. In LSP for configure outputs, is it set for the correct LAN connection?
7. For the cable that comes from the Switch / Access Point is it plugged into the Ethernet input jack on the Etherdongle correctly?
(The Laptop connects to the silver MagJack input side of the Etherdongle, then out on the other connector on the Etherdongle to the Input of the Lynx Express into the DMX input)
8. Does the test mode on the Lynx Express work and light up in stand alone mode on all channels?
9. On the Laptop, are any virus checkers running (if so turn them off for now)
10. Does your Router support Multicast (on mine it isn't filtered as default, so it passes the Multicast packets, but some routers filter multicast, or don't support passing multicast packets, so that might be causing your issues as you go through the router)
Below is what the Output configuration should look in LSP (your Lan connection might be different to mine though)