There are a number of high speed Internet providers in Rancho Santa Fe and surrounding areas.
If you live in the Covenant of Rancho Santa Fe (ie. you pay HOA dues to the RSF Association), then by far the best option is RSF Connect run by Race Communications.
If you live in nearby Solana Beach or Encinitas, then Ting Internet is your best choice.
Both these providers offer fiber optics to the home with 1 Gigabit/second Internet.
Starlink is offering high speed low latency Internet to residents around the Rancho region who do not have access to other high speed options.
RSF Connect provides gigabit Internet (1,000 Mbps) to all RSF Association residents over an all fiber optic network. It also provides phone service and the equivalent of satellite or cable TV.
When the fiber network was built in 2018/2019, residents were responsible for installing their own conduit from the street to their house. Your particular house may or may not have had this done (check with previous owner). Race Communications, the RSF Connect operator, will do this work for you for an installation cost that is often $2,000 to $3,000. In addition, you will need to wire up your house for robust WiFi. This page gives contact information for local technology integration companies that can co-ordinate this for you.
Race Communications is the Internet Service Provider offering gigabit fiber over this network to residents. Click here to go to Race's RSF Connect order page.
If you live in Solana Beach or Encinitas, then Ting Internet will be the most reliable and high performance Internet option. They deliver 1 Gbps Internet over a recently built all fiber to the home network.
While you do have other options in Solana Beach and Encinitas, they are based on legacy technology and won't be as fast, efficient or reliable as Ting's all fiber optic network.
If you live in an underserved community near Rancho Santa Fe (or anywhere for that matter), high speed Internet salvation comes from the sky for you from Starlink, a division of SpaceX. Satellite Internet has traditionally been a last resort due to slow speeds and huge latency, but Starlink is a different breed. Instead of relying on geosynchronous satellites 22,000 miles away in high orbit, Starlink uses a large constellation of thousands of satellites in a very near 350 mile high orbit. The only caveat is that you must have unibstructed views of the entire northern sky (down to 30 degrees above the horizon), so often an antenna pole or roof mount is needed.
San Diego Broadband provides high speed consumer and business class Internet access via a dish antenna that can see line of site to one of two mountains in the region (Black Mountain and Lake San Marcos). Their consumer prices are competitive with other consumer offerings and they have "no data cap" business plans.
SD Broadband tops out at about 30 Mbps, so I would only look at them if you had no other high speed choices. But their service is good and the link is generally reliable.
Depending on where your house is located, you could get no Internet connectivity, 1-3 Mbps download (via copper DSL), or up to 25 Mbps download speeds (if they have installed fiber to the curb in your area).
Click here to visit the AT&T availability web site to determine what is offered at your house.
Depending where you are located, you might have access to Internet from either Spectrum or Cox. Check their websites for availability at your address and Internet speeds that are available.