It means that device is configured with the erg.com domain, so it tries to request it when obtaining a lease. Since that domain doesn't belong to your router, it's ignoring it.
This is probably a (poorly configured) business laptop that's configured for the domain used by their company (and which ignores best practices by using a public TLD on a private network).
I hope this helps!
Thank you. Having had the issue myself for years, and having just discovered how to stop it, I thought that might benefit others as well.@FernandoF, that is valuable to know. Thank you.
2 years later? No.
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