Is it always the same laptop? Are the others connected to the same wifi base station? Have you recently increased the number of computers served by this base station (or whatever supplies DHCP services to this cluster of computers)? Does that DHCP server have a large enough address pool (based on total client base and lease length)?
thanks so much. yes. its always the same laptop and at least two other Mac/Pros are connected at all times, with one intermittently. no changes in home computers or load otherwise. the server is a big one: comcast, and should be pretty large. the other computers have never had this problems so we were trying to figure out if this was a one-time problem with this computer. we reset the whole thing last night according to a couple of things that were suggested on the community. it worked for a while and then happened again this morning.
thanks for trying to help us !
Point of terminology: Comcast is a network provider, a company, not what I meant by "DHCP server," which is a piece of equipment or a service operated on a piece of equipment.
The DHCP server is in charge of handing out dynamic IP addresses to client computers when requested. The fact that your laptop is using a self-assigned IP address tells us that it looked for a DHCP server but either it could not find one or the DHCP server it found did not supply an address.
Comcast should have provided you a piece of equipment to interface between their cable system (probably attached by coax) and your local computers (attached by ethernet cable and/or wifi). That's a modem (specifically a cable modem). I've never been a Comcast customer, so I don't know whether they place the DHCP server in the modem or upstream of that.
Do you have any router of your own between the Comcast modem and your computers, or do your computers connect directly to the modem (either by wifi or by ethernet)?