First off, review if device using DHCP or Static network configuration.
Printers and scanners tend to be set to static settings and are at times left out during cutovers.
Some printer/scanning devices have general network configuration such as (IP, Gateway, Subnet) separate from DNS server settings. Refer to device documentation if unfamiliar with menus and be sure to document current settings.
Make sure the printer has the correct network settings including gateway, subnet, an IP as per configured when OmniShield wizard was ran for the subscription. Make sure it is not using ISP DNS servers (ISPs tend to block DNS requests originating outside their network, in this case from OmniShield network when connecting thru an OmniShield subscription***).
- Review logs on printer or scanner to understand what failure message is being recorded by the source device.
- Verify IP/Subnet/Gateway settings are correct
- Verify problem device is not using ISP DNS servers
- Verify you are about to ping printer/scanner from another device connected to same OmniNet network? If not check network settings on printer/scanner
- Check if configured email server is ISP Email server. If so, check if ISP is blocking the connection since its now coming from OmniShield Network. Some providers will allow the connection if the SMTP connection is made using secure SMTP. ISP will be required to answer this if it is their email server/relay
- Check with email hosting provider if OBR public IP can be whitelisted
- Emailing via ISP: Check with ISP to make sure they are not blocking
- Emailing via ISP: Check with ISP what authentication level is required for a device to send email through them when sourcing from outside their own network
- If printer has static settings, does the printer work if switched to DHCP? If so, what is different from static settings?
- If using FQDN for email server, does using an IP instead resolve?
- (Advanced) Printer with a static IP: Disconnect the printer temporarily, use its static IP configuration and mimic network settings dns server settings. Use telnet client to test outbound connectivity to target email server. This may yield for detailed error messages.
- If you suspect OmniNet security is the culprit, you can temporarily turn off security and test again. Turn back on when done testing.
***ISP Provided Email Services: ISPs may blocking incoming SMTP connections from another network. When switching to OmniShield your customers connections will be sourcing from OmniNet network and not their own. Be careful to review with ISP email hosting provider to make sure this will not be an issue. Some allow connections as long as its secure SMTP. Again consult with ISP Email hosting provider as to whitelist the IP or to let you know what ports to use for SMTP if coming from outside their network.