[drizzt09]

Your echo will be going out of your network to Amazon skills server. Then needs to come back into your network to your hosted server. So you will need external IP/name setup. You will need routing in your router to point to the right 192 internal IP. Most routers nowadays have ddns configurations that you can add a hostname with a 3rd party. Noip.com etc. Then you can create a free hostname on the 3rd party. Point it to your current external IP. If your external IP changes, the config in router will update 3rd party so route doesn't break. Then you can configure your skill with hostname instead of ip.

Could someone please give a bit more detail about self hosting

the lexigram instructions just sort of stop at that point

presumably I need to copy some code to my webserver but it doesn't say what exactly

I have a copy of apache2 running locally and i have mod_wsgi installed and working

Everything seems to working and the skill has been deployed 

my echo dot says "Unable to resolve hostname for endpoint Resource [https://192.168.0.xxx], Type [HTTP], Region [DEFAULT]"

I presume I'm going to have to set up a nameserver rather than use an IP address 

but i haven't installed anything locally onto webserver, so I'm a bit puzzled what needs to go where

any hints gratefully received

Thanks for info regarding ddns, but I'm still unclear what needs installed on my local webserver

Sorry. That much I don't know. I have not setup local server version. And I'm still running the old version. Haven't revisited this setup in about a year. Lots has changed. I just saw your question and knew how to answer networking because I use it for other things (Minecraft lan play outside of lan)