A 2018 Gulden (NLG) update broke Electrum server integration for third party wallets such as Coinomi. Our immediate calls for assistance at their github were met with hostile and unhelpful comments - after a while, our request was even tagged as "off topic", closed and the offensive messages removed by the author.
Therefore, the coin was delisted from Coinomi on the first week of October 2018. Via announcements on our social media weeks in advance, Coinomi users who had Gulden balances were kindly requested to send their NLG to Gulden's own wallet (which they deemed "sufficient" in their correspondence) or to an exchange to trade it into different coins. No other coins were affected, including e-Gulden (EFL) which is a different project.
We apologize on their behalf for the inconvenience.
Our NLG servers are now offline, and current versions of Coinomi no longer have the option to add new NLG wallets. If you missed the deadline, you won't be able to send the coins directly from within the app. Of course, there is nothing to worry about. There is no risk of coin loss. With Coinomi you are in full control of your coins no matter what happens to our servers. To move your funds extract the private keys of the addresses where you have coins, and import/sweep them into an official desktop* NLG wallet. Please contact their support for specific instructions (remember never to share your keys or phrases with anyone).
* The Gulden Android wallet does not support importing/sweeping keys, and their software also uses a different BIP44 standard as Coinomi. Using your Coinomi recovery phrase will not work (besides being a security risk, potentially giving an attacker access to all of your coins, not only NLG).