Just as an idea try connecting to a non NA server. See if its stable. If it is stable then nothing at all SE can do on the issue even with complaining to FIoS as they won't really care. However if it is stable also then stop saying its just FF and that your having trouble connecting to any server hosted in Montreal, Canada area. Thing is the ISPs love to treat gamers as 3rd class customers because they know their is usually very little option in the US to change to a different ISP.

I remember years ago with an ISP I won't mention *cough* *comcast* *cough* when my internet was completely down as in NOT functioning at all. I called them up and they actually referred me to their online self troubleshooting guide telling me I should go there and try their trouble shooting tips. Amid probably minutes of 95% of my words being very harsh swear words they finally escalated me to the next level technician. The next level technician seemed to understand that I couldn't access the online trouble shooting guide since my internet was out after I explained it.