Hello @Sharpraba,
This error indicates that your full node coin adapter cannot connect to your wallet. You should first check where your wallet is installed.
Since 192.168.* is in a private address space (https://en.wikipedia.org/wiki/Private_network), this is probably an address on your local network. If your webserver is on a hosting provider, you will not be able to connect to a local wallet (without setting up NAT and using a static IP). It’s best to run your wallet service on a fully managed host and use its public IP address.
On the other hand, if you are running the plugin locally (such as on an integration/test server), then it’s ok to connect to a local wallet on the same network.
In general, your WordPress server should be allowed to connect to your wallet server via TCP to the port that you’ve specified.
Since you’re installing a full node wallet, see the relevant article: https://www.dashed-slug.net/bitcoin-altcoin-wallets-wordpress-plugin/installation-instructions/
If you are NOT certain that you need to setup a full node, please see an introductory article about the different types of coin adapters available: https://www.dashed-slug.net/howto-choose-between-available-coin-adapters/
Please let me know if you have any questions about any of this.
with regards