If I'm not wrong then you need to specify your local IP address if you're connecting it to your own node. According to
https://bitcoiner.guide/blue/ (it uses Electrum btw) you just need to type your local PC address and then create your wallet as usual. Check your router to check your local PC address (or use the network properties/something similar). You might find more help if you post this on the Wallet sub-board, so I suggest doing that. CMIIW.