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ASA 5505 no longer gets DHCP from new cable modem.

Here is an odd one. This happened at work a couple of weeks ago and today at home. We were using an ASA 5505 connected to a cable broadband connection for guest Internet services. Rogers cable notified us that they needed to swap our existing modem with a new one. After they did, the ASA just would not grab an address via dhcp. It just kept showing no matter what I did. I bounced both devices. Admin shut down the switchport on the ASA and the vlan interface, brought them back up, same thing. Did all of this several times and still it just kept showing I replaced with a cheaper SOHO Linksys device and it works fine now on the first power up.

Fast forward to today. I upgraded to a 150/10 service from a ATPIA service provider ( the same incumbent that I had issues with at work). I called a couple of days ago to get the provisioning ball rolling and my Internet died this morning, so cool my new modem must be provisioned. I race home on a quick coffee break to swap modems. I swap them, wait for the online light on the new one to come on, and then power cycle my ASA 5505 at home. Run upstairs to confirm all is well. No..same bloody thing! The vlan interface is showing from DHCP. Same darn thing that happened

at work with a cable connection and an ASA. Recycled both devices and headed back to work. I still cannot access my firewall remotely so I can only assume the situation has not changed.

Any thoughts?


ASA 5505 no longer gets DHCP from new cable modem.


did you try this on the vlan interface ?

no ip address

ip address dhcp



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