Is fiber optic internet

In my opinion, yes. My sound quality was improved when I used an optical cable as described below 

My Ethernet source drives a netLINK Ethernet Media Converter model HTB-GS-03 with a fiber optic output driving a fiber optic cable to my Infigo Audio IS-1 streamer.  A 5V wall adapter powers the netLINK.  The streamer’s only digital output is USB to the DAC.  Infigo chose USB as the sole output format because done right it provides ultimate performance.  Any other format would increase cost while limiting bit rate, sample rate and ultimate performance.

Fiber optic isolation in this case improves audio quality by eliminating network noise and jitter. This separation between the ‘dirty’ network and the clean audio chain ensures that RF and EMI interference, as well as high-impedance leakage currents from network devices, do not degrade the audio signal. As a result, digital music reproduction is cleaner, quieter, and more transparent, providing a more natural and lifelike sound experience. 

Thanks for the response.  With that in mind, do you think if the internet source was from a fiber source, that alone would affect sound?

@rivinyl 

I believe a fiber internet source alone does not inherently affect sound quality in audio streaming, as digital data transmission ensures bits arrive intact regardless of the medium.  We need others to respond.  

FYI - Fiber optics can reduce electrical noise, RFI, and EMI compared to copper connections by using light signals immune to electromagnetic interference. In high-end audio setups, this may lower the noise floor, improve timing precision, and yield a cleaner soundstage when using fiber media converters between network components.

Yes, a friend of mine put in a $20 fibre cable into his streamer and found an immediate improvement on his very expensive system ($200k). I have been using fibre from a network switch that converts Ethernet to fibre and then connects fibre to a Sonore OpticalRendu which converts to USB into my DACs.

At one time I had 3 low-cost network switches, 3 OpticalRendus, and 3 DACs in 3 rooms. I used ROON to control everything.

Sonore Optical Rendu Complete System Streamer - Less than 1/2 Off For Sale - US Audio Mart

I prefer a network switch to do the conversion instead of the dedicated Ethernet to Fibre converters. Those failed on me several times, the network switches are rock solid (from $49 to $150 for my 3 switches)

Fibre cable is made of glass and cannot carry analog noise into a DAC like an Ethernet cable.

I moved from 800Mbps cable internet, running on a pfSense server to 10Gbps fiber, and immediately, the jitter measured only a fraction of what the cable had as well as latency.  Running a pfSense server on an old i7-4770 with 32GB RAM and Intel server NIC's is ridiculously overkill, but ill never need another router.  But I do need to update to better NIC's and switches to get anything over 1G speeds.