Thanks for the answer.
I have static IP 5.146.4.167
After some testings around I have figured out that if I use the IPv6, the adapter is responding but the padlock is closed. I’m unable to open the padlock and no address is generated.
Now I have disabled the IPv6 in the Router and restart the server. Now I have only IPv4. But the BTC Wallet adapter is not connecting to my Bitcoind.
Then I have installed the newest Dogecoind on my server. I see, that there are the same problems as Bitcoin. No remote connection under IPv4, responding under IPv6 but padlock closed.
The wp error log cannot help. There are errors like “Failed to connect to 5.146.4.167 port 8332: Connection refused” or “Could not get info about coin with symbol BTC: Adapter for “BTC” did not respond to the getnewaddress RPC command with a valid address string.”
Other Coins like Litecoin, Feathercoin or eMark running fine.