If you are having trouble viewing your HubSpot-hosted site on a specific network (e.g., your work or office network), this can indicate that the network has been configured to use an internal DNS structure.
To troubleshoot this issue, try accessing your website from your mobile device while your Wi-Fi is switched off in your device's settings. If you are able to load your website successfully, there is likely an internal issue on your network that needs to be resolved. Visitors outside of the network should be able to view your site with no issues. If the internal DNS structure has a specific record entered for your domains that isn't matched to the records listed in your domain manager for your connected HubSpot domains, the request from your website browser to the hosting server (HubSpot's server) will not be able to complete.
To verify whether your network is using an internal DNS configuration, reach out to your network engineering/IT team. If your network uses an internal DNS structure, pass the team your HubSpot-assigned CNAME records from the domain manager and have them update the records in their configuration. The team may also need to flush the DNS cache.