Like many online services and systems from time to time Flywire may be down or have a reduced service for scheduled maintenance or other reasons (such as outages of other systems that impact multiple online facilities).
Usually any downtimes or service outages will be for a short period of time, but you can check Flywire's status online.
This status dashboard will also show if there are any scheduled maintenance planned that might mean some services won't be available, might be slow or might be less reliable.