On another hard wired box, ping the UAP-AC and leave it running. What would be ideal to determine is, if there is any packet loss to the AP itself, or if the problem exists solely between the UAP and the Bike.
Are you running your ssid with both 2.4 and 5ghz on the same ssid? Try creating another ssid dedicated solely to 2.4ghz and configure the Peloton to use that. The UAP (if running a UAP controller software) also has lots of info to help determine what's up. Explore that. Did you get the UAP after the 6610 or before? If before, was it working fine before the 6610?
I would find it very surprising if the 6610 caused problems for one device on wifi while all others are ok. This seems unlikely. Other things can cause havoc, eg at my old house when my neighbors had a kid, my 2.4ghz wifi went to hell as they had a wireless baby monitor on the same frequency. Regardless of the channel, it was crap. Once I moved to a less densely populated area, the exact same wifi router was totally fine.