I bet you're having the same issue I am, as I also have Spectrum.

https://forum.square-enix.com/ffxiv/...=1#post6715700

tl;dr It appears to be packet loss, due to routing through unstable ntt.net addresses. One of the links I posted there also suggested reporting it here:
https://secure.square-enix.com/enqt3...ef5c9b5c95e893