NTA.

From the sound of it, you told Sister as soon as she woke up from her nap that you had changed out the router. Anyone who deals regularly with networks knows that a new router nearly always means computer settings would need updated; not your fault she waited hours to even think of it.

Moreover, while shingles is highly contagious, and can be spread when a person comes into contact with fluid contained in the blisters, meaning the virus can be spread by direct contact with the lesions or by touching any dressings, sheets or clothes soiled with discharge from the spots, shingles are a reactivation of the chickenpox virus, it's not just a random yeast, mite, or other rrash that results from inadequate personal hygiene.