My lightning node URI is not visible I did set up a mainnet c-lightning node by following the guide.
https://medium.com/@dougvk/run-your-own-mainnet-lightning-node-2d2eab628a8b

I noticed my node is visible on https://lnmainnet.gaben.win/ but the URI is unknown. Is there some settings I need to check on my server?
when starting lightningd, you want to add the option:

--addr=[insert your IP address here]

so maybe when starting your lightning node, at your command line you would enter:

lightningd --alias DavideRivola --network bitcoin --log-level debug --port 9735 -ipaddr 192.168.1.1

Where 192.168.1.1 you would of course, put your own IP address.

Also, since you are probably unaware of this as well, in case you want to choose the port, use the --port=9735 option and just change the port to which you want to use. Everybody pretty much uses port 9735 though. Make sure that this port is forwarded on your internet router and is not blocked by your firewall either.

Also, if you want to choose the color that represents your LN Node on the #recksplorer site, you can use the following option --rgb 00cc00 where 00cc00 is the RGB code you would like to use. (In this case I have chosen green, because, well..look at my name :) )

Use this site to find the corresponding RGB Code for the color you want to use: http://www.color-hex.com/

use the command lightning-cli listconfigs to check what you have configured for your node to make sure everything is right after it is up and running.