[michaelsbradley]

If your validator isn't online and/or not able to "do its job" in the allowed for time-period, then it will be penalized.

The penalty for missing one validation is small; the penalty for missing a block proposal is also not huge, but bigger than the penalty for missing a validation. Penalties would pile up over time if a validator is offline for an extended period.

Long story short: if you intend to run an ETH2 validator, you should be reasonably sure it will be able to run well-connected to the Internet for extended periods of time. Intermittent and brief periods of downtime would not have a substantial economic impact on your validator, but extended periods of downtime would be bad.