Does it block it right away? If it works for a minute or two (or ten) then cuts off they might be doing more deep heuristics, but that's usually something only

Does it block it right away? If it works for a minute or two (or ten) then cuts off they might be doing more deep heuristics, but that's usually something only governments do (ex, great firewall). They also might have just blocked the IP range of your VPN because you connected to it in a different mode before and the network just remembers that.