Exporter starts behaving weirdly then destination host in config is unreachable

[cognoz]

Use case: we have running several cloud instances (CentOS 7.6) with mtr-exporter(in systemd)
In config I specified neighborhood instances ips like this:

• name: "10.0.30.36"
  alias: internal
• name: "10.0.30.25"
  alias: internal2
  ...

If one instance from config goes down exporter starts behaving very weirdly:
sometimes I receive "Connection refuse" on /metrics endpoint
sometimes I got all metrics
sometimes I got only prom/go related metrics