Yes, the polling 200 status indicates nothing is wrong. Everything you're seeing is completely normal of nodes Socket.IO.
Furthermore, polls are done on port 80 http, so it would never be blocked. Webscoket traffic in general is done ona range of ports, none of which ISP's filter (I've worked for an ISP). The only port I know that SOME NorthAmerican ISP's block is SMPT incoming and even that is rare.