Gupax can use nodes which don't exist
## OS & Version:
All OS

## Bug
Gupax can select xmr.theuplink.net which doesn't exist anymore. It even shows ping time for xmr.theuplink.net, but it's probably pinging some other node.

![u70hu9ak732c1](https://github.com/hinto-janai/gupax/assets/15806605/321cc190-3720-4364-9f56-483ad3ca5d04)
