I can’t access ncbi, even when I change the browser, but I can access it from another location. Is it an address issue?

The issue you describe—being unable to access the National Center for Biotechnology Information (NCBI) website from one location while access is possible from another—is almost certainly an address-related network problem, specifically a form of geolocation-based or network-based blocking. The core mechanism at play involves how your internet traffic is routed and how the destination server or intermediate network nodes respond to requests from your specific IP address. When you change browsers on the same machine at the problematic location, you are still using the same underlying network connection and public IP address assigned by your Internet Service Provider (ISP) at that location. Since browser changes do not alter your network origin, the persistence of the problem points decisively to a factor outside your local device, namely your network's IP address being denied, filtered, or misrouted.

Several specific address-related mechanisms could be responsible. The most common is that the IP address range assigned to your ISP at the inaccessible location has been blocked by NCBI's security or firewall systems. This can occur if that IP range was previously involved in activity perceived as abusive, such as excessive automated querying, which NCBI monitors to prevent server overload. Alternatively, the blocking could be intermediary: some institutional, corporate, or national networks implement filtering that restricts access to external sites like NCBI. If the inaccessible location is a workplace, university, or a specific country with regulatory firewalls, the blockage may originate from that local network administrator or national internet policy, not from NCBI itself. A less likely but possible technical cause is a routing issue or DNS problem localized to your ISP at that address, where the domain name "ncbi.nlm.nih.gov" fails to resolve correctly or the network path to the server is broken.

The implications of this diagnosis are practical. It confirms that troubleshooting should focus on the network environment of the inaccessible location, not on your personal device configuration. To verify the hypothesis, you could attempt access using a different network at the same physical location, such as switching from a wired connection to a cellular mobile hotspot. If access is restored, the problem is definitively your primary network's IP address. For resolution, if you are on a private network, contacting your local IT support is necessary, as they may need to whitelist the NCBI domain or address an internal firewall rule. If you are on a residential connection, contacting your ISP to report the issue is a step, though they may be limited in addressing a block imposed by NCBI. In such cases, using a VPN service could circumvent the block by masking your originating IP address, though this may violate the terms of service of some institutional networks and does not address the root cause. The scenario underscores how access to critical public research infrastructure can be inadvertently compromised by network-level security measures, creating uneven access for users based solely on their point of network entry.