Yes, definitely doing the "dig" command from the server on which Simutrans-Experimental is running.
Ahh, wait, I think that I know what the problem is. Some considerable time ago now, I could not get the DNS resolution to work in the announce server part of the code for reasons which I have never been able to establish, so I changed the code in simversion.h as follows (old parts commented out):
/* Server to announce status to */
//#define ANNOUNCE_SERVER "servers.experimental.simutrans.org:80"
// Temporary workaround for DNS problem
#define ANNOUNCE_SERVER "220.127.116.11:80"
The 18.104.22.168:80 is the part that I am guessing is no longer applicable. Unless and until I can find a way of resolving the basic problem (I spent hours and hours on it before with no success, and do not remember now what I tried, so this would probably require assistance from somebody who understands networking code), I shall need to update the IP address. Should it be to 22.214.171.124:50 or 126.96.36.199:80?