172.20.21.1 router login
To open the admin panel, type 172.20.21.1 into your browser's address bar. If the page does not load, this is probably not the gateway address on your network — see the checks below.
172.20.21.1 router passwords
Where to find them:
- The label on the underside or back of the router — most manufacturers print the default admin username, password and Wi-Fi key there.
- The quick-start card or manual that came in the box.
- Your ISP's account portal, if the device was supplied by them — many set a unique password per line rather than a shared default.
No username and password combination is recorded for this address, so none is offered. The device answering at .1 will have its own defaults, normally printed on a label on the chassis or listed in the setup guide. In a business or lab environment those factory values are frequently replaced during commissioning, in which case the change should be documented internally.
How to log in to your router
Type 172.20.21.1 into your browser's address bar and press Enter. Type it by hand rather than accepting an autocomplete suggestion, which often fills in a different address you visited before.
If the browser reports that it cannot reach 172.20.21.1, this is not the gateway address on your network. On Windows run ipconfig /all and read the Default Gateway line; on macOS open System Settings, Network, Details, TCP/IP; on Linux run ip route and read the address after "default via".
If the login page loads but rejects your credentials, and you have never changed them, use the defaults printed on the device's label. If they have been changed and nobody knows the new password, a factory reset is the only way back in.
If you do not know the password
Where the login has been lost, look for the password in the site's own records before doing anything drastic; many gateways also expose a console or recovery mode that requires physical access. A hardware reset restores factory state, discarding VLANs, static routes, firewall policy and DHCP settings, and reverting any wireless name and passphrase to the printed label values.
172.20.21.1 belongs to 172.16.0.0/12, the middle-sized private range. It spans 172.16.x.x through 172.31.x.x, uses a 255.240.0.0 mask and contains 1,048,576 addresses. This block causes more confusion than the other two, because 172 addresses outside that 16-to-31 window are ordinary routable space; only the reserved portion is private, and 172.20 sits comfortably inside it. Mid-size business networks, lab builds, VPN subnets and Docker bridge networks all draw from here.
The working scope for this address is 172.20.21.0/24, usable from 172.20.21.1 to 172.20.21.254 with broadcast at 172.20.21.255. The .1 position is the customary home of a segment's router or firewall, and a handful of other addresses in the same /24 are documented alongside it. Readers usually arrive wanting to reach the gateway's admin page or to check that the subnet is behaving as designed.
Whois information for 172.16.0.0/12
# ARIN WHOIS data and services are subject to the Terms of Use
# available at: https://www.arin.net/resources/registry/whois/tou/
#
# If you see inaccuracies in the results, please report at
# https://www.arin.net/resources/registry/whois/inaccuracy_reporting/
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# Copyright 1997-2024, American Registry for Internet Numbers, Ltd.
#
NetRange: 172.16.0.0 - 172.31.255.255
CIDR: 172.16.0.0/12
NetName: PRIVATE-ADDRESS-BBLK-RFC1918-IANA-RESERVED
NetHandle: NET-172-16-0-0-1
Parent: ()
NetType: IANA Special Use
OriginAS:
Organization: Internet Assigned Numbers Authority (IANA)
RegDate: 1994-03-15
Updated: 2013-08-30
Comment: These addresses are in use by many millions of independently operated networks, which might be as small as a single computer connected to a home gateway, and are automatically configured in hundreds of millions of devices. They are only intended for use within a private context and traffic that needs to cross the Internet will need to use a different, unique address.
Comment:
Comment: These addresses can be used by anyone without any need to coordinate with IANA or an Internet registry. The traffic from these addresses does not come from ICANN or IANA. We are not the source of activity you may see on logs or in e-mail records. Please refer to http://www.iana.org/abuse/answers
Comment:
Comment: These addresses were assigned by the IETF, the organization that develops Internet protocols, in the Best Current Practice document, RFC 1918 which can be found at:
Comment: http://datatracker.ietf.org/doc/rfc1918
Ref: https://rdap.arin.net/registry/ip/172.16.0.0
OrgName: Internet Assigned Numbers Authority
OrgId: IANA
Address: 12025 Waterfront Drive
Address: Suite 300
City: Los Angeles
StateProv: CA
PostalCode: 90094
Country: US
RegDate:
Updated: 2012-08-31
Ref: https://rdap.arin.net/registry/entity/IANA
OrgAbuseHandle: IANA-IP-ARIN
OrgAbuseName: ICANN
OrgAbusePhone: +1-310-301-5820
OrgAbuseEmail: abuse@iana.org
OrgAbuseRef: https://rdap.arin.net/registry/entity/IANA-IP-ARIN
OrgTechHandle: IANA-IP-ARIN
OrgTechName: ICANN
OrgTechPhone: +1-310-301-5820
OrgTechEmail: abuse@iana.org
OrgTechRef: https://rdap.arin.net/registry/entity/IANA-IP-ARIN
Other documented addresses in 172.20.21.0/24
The 172.20.21.0/24 subnet runs from 172.20.21.1 to 172.20.21.254, with 172.20.21.255 reserved as the broadcast address. These are the addresses in it we hold router login details for.
All addresses we cover here
4 addresses in this subnet have a page; the most looked-up are listed here.