Public IP address required for 3Business Broadband Max

[cyber_business]

Hi,

I have a 3Business Broadband Max service and I would like to obtain a public IP address on my connection.

I contacted Three Technical Support, and they advised me to try the following APNs:

• open.internet.public.static
• open.internet.public

However, with both APNs, my modem is still being assigned a private WAN IP address in the 10.67.x.x range. This indicates that the connection is still operating behind CG-NAT.

I believe that an additional service or configuration may need to be enabled on the SIM card or account before the public APN can assign a public IP address.

Could someone from Three please review the provisioning of my service and confirm what needs to be enabled?

I only require a public IP address. It does not need to be static.

Thank you.

[Three_Niall]

Hey @cyber_business thanks for posting here, if you pop through to me on PM along with your full name, broadband number, address and date of birth I'd be happy to to have a look for you or alternatively you can speak to our broadband team on 1913.

[cyber_business]

Hi @Three_Niall

Thanks for your message , I've just sent you the DM with the details requested .

[Three_Niall]

Hey @cyber_business I can see that you have sent me a PM and I will respond to you there. 

[cyber_business · Accepted solution]

Hi @Three_Niall 

As mentioned this morning, I contacted Three Technical Support by phone regarding the public IP configuration on my 3Business Broadband Max service.

The open.internet.public APN was already configured on the modem, but the WAN interface continued to receive a private IP address in the 10.67.x.x range. It appears that the required public-IP profile had not been enabled on the SIM or customer account.

Following the support request, the necessary profile now appears to have been activated. I have checked the modem again and can confirm that its WAN interface is now receiving a dynamic public IPv4 address.

For future reference, and to help other customers with similar requirements, Three provides three different IPv4 connectivity options:

1. Default service: Private IP behind CGNAT

APN:3FWA.ie

With the default APN, the modem receives a private IPv4 address on its WAN interface. Three then performs Network Address Translation upstream, allowing multiple customers to share public IPv4 addressing.

This configuration is suitable for normal outbound Internet access. However, because the connection is behind carrier-grade NAT, unsolicited inbound connections cannot normally be forwarded directly to the modem.

This can also create limitations for traditional site-to-site IPsec VPN configurations where the Three connection is expected to accept inbound IKE/IPsec sessions on a directly reachable public IPv4 address. Some outbound-initiated or dial-up VPN configurations may still work, depending on the firewall, VPN design and NAT traversal support.

2. Dynamic public IPv4 service

APN: open.internet.public

With the correct profile enabled on the SIM or account, this APN assigns a dynamic public IPv4 address directly to the modem’s WAN interface.

The address is public and Internet-routable, but it is not permanently assigned. It may change when the mobile data session reconnects, when the modem restarts or when Three renews or reprovisions the connection. No specific IP retention period should be assumed.

This option can be suitable for:

• Dial-up IPsec VPN configurations.
• VPN tunnels where the Three-connected firewall initiates the connection.
• Deployments using dynamic DNS.
• Remote-access services where a permanently fixed address is not required.
• Environments that require a public IPv4 address but do not want a permanent, predictable Internet-facing address.

It is important to note that entering the APN manually may not be sufficient. The dynamic public-IP profile may also need to be enabled by Three against the SIM or customer account.

As of today, this service is provided free of charge, but a ticket must be raised with the Technical Support team to enable the required profile on the account.

3. Static public IPv4 service

APN: open.internet.public.static

With this service, the modem receives a public IPv4 address that remains fixed. This is generally suitable when a business needs a predictable address for:

• Site-to-site IPsec VPNs with fixed peer addressing.
• IP allowlisting.
• Remote monitoring or management.
• Services that require a consistent source or destination IP.
• Third-party systems that cannot use dynamic DNS.

This requires a separate static-IP service to be enabled by Three and is only available with eligible business broadband services.

During my support call, the static-IP add-on was quoted to me at €10 per month plus VAT. This was the price communicated specifically during the call and should be confirmed directly with Three for each account, as public support information may show different or older pricing.

Important provisioning requirement

If open.internet.public or open.internet.public.static continues to assign a private address such as 10.x.x.x, the issue may not be the APN configuration itself. Three may need to activate the appropriate public-IP profile on the SIM or customer account.

In my case, once the profile was enabled by the Technical Support team, the modem began receiving the expected dynamic public IPv4 address through.

I hope this information helps other Three customers who require a public IPv4 address for VPN, firewall or remote-access purposes.

[Three_Niall]

Hey @cyber_business thanks for posting here and delighted that this got sorted for you. 

I appreciate your breakdown of the situation however once the broadband team have applied the Broadband Public Provisioning to the account then the Public IP address will be activated on the device in the format Open.Internet.Public as this APN won't work if it's entered in all lowercase like described throughout the post. For future users who have had the Public Provision added by an agent you will need to make sure the APN is in the correct format for this to work.

[cyber_business · Accepted solution]

Hi @Three_Niall ,

Just for clarification and future reference, we initially configured the APN using capital letters, but the modem continued to receive a private IP address.

After contacting Three Technical Support, it appears that the required dynamic public-IP profile was enabled on the SIM or customer account. Once this was completed, the modem successfully received a dynamic public IPv4 address.

From a technical and standards perspective, the capitalisation of the APN should not affect the result. APN naming and encoding are defined by the international telecommunications standards organisation 3GPP.

3GPP TS 29.274 specifies that the APN field is encoded according to 3GPP TS 23.003. In turn, section 9.1 of TS 23.003 states that the APN follows DNS naming syntax and explicitly confirms:

“The case of alphabetic characters is not significant.”

The relevant specifications can be reviewed here:

• 3GPP TS 29.274, section 8.6: Access Point Name
• 3GPP TS 23.003, section 9.1: Structure of APN

Therefore, the following APN values should be treated as equivalent:

open.internet.public

Open.Internet.Public

OPEN.INTERNET.PUBLIC

In this case, the issue does not appear to have been caused by the use of uppercase or lowercase characters. The same APN started working only after Technical Support processed the request, which strongly suggests that the required dynamic public-IP service or profile needed to be enabled on the SIM or customer account.

Nevertheless, I recommend using the lowercase format documented by Three:

open.internet.public

This avoids any potential compatibility issue with modem firmware or local APN validation.

For other customers experiencing the same issue, if open.internet.public still assigns a private WAN address such as 10.x.x.x, they may need to contact Three Technical Support and request that the dynamic public-IP profile be enabled on their account.

[Three_Niall]

Thanks @cyber_business for your general research in the previous comment 😊

For any Three Ireland customers facing a similar issue in the future, I would recommend contacting our dedicated broadband team on 1913 where our team can apply the Public IP provisioning if available on the account and then applying the APN Open.Internet.Public to match the APN that the team would apply on the back end.