Ok, some background. Landlord here was providing internet as part of the utilities charge. He turned it off for some damn reason. Guy in the room next to me gets fios in response and offers to share the line with me. Unfortunately, he completely misunderstood the terms of the service and offered me a connection for about $ 10 / mth. When the installation bill came in it was for $ 140. He then said I'll allow you service for half the bill, and I agreed. I paid him $ 70 for my share, and he (then apparently) promptly blocked me from service, and asked for more to get connected. I admit, I'm a senior citizen (and maybe slow on the uptake), but do I really need to be treated like this? Screw him. I consider it a small price to pay to find out his true character and intentions. Btw, I'm allowing him to think that I'm stupid.
Look for a mobile connection at one of the phone companies around your area. They provide a small device that serves a connection like a router. You will connect to it though wifi, the very same way you do now. Then you won't need to depend on anyone to get internet. Campers, truck drivers and van owners use it on a regular basis when they are on route.
What a frickin' disgusting landlord and neighbor you have. People can be terrible. Give that neighbor of yours a disgusting look every time you see him.
If you have time, just file a small claim in court. He shouldn't be treating neighbors like that. And also you can call FIOS to register a complaint. https://www.nycourts.gov/courts/nyc/smallclaims/forms.shtml
For €6 per month I get an Internet connection of 500Mbit on download and 250Mbit upload. And the installation was free. I actually pay for 2 landline connections from separate providers just for the occasion outage on one, I can quickly switch to second. And not have to use the 5G dreadful mobile conections of which I also have 2 (separate providers). So I really don't get this sort of problems, they are completely out of my world.
He's got a wifi router I assume. Just figure the password for it, find the key to connect to the router, and get it for free. Get yourself connected.