Thanks, I havent heard of that before.
I ran pfctl -vss and when it hangs it comes up with a SYN:Closed and it is showing the wscale in the range 0 to 2 range.
So I have changed this net.inet.tcp.rfc1323: 1 -> 0 and retried the web site and so far its looking much better. I think you might have hit the solution in one go !
I think I will have to read around this topic more. Maybe OpenBSD should ship with the option at 0 if lots more Linux boxes are using scaling by default now.
So is what this rfc1323=0 is doing is disabling the ability for allowing the packets to use the scaling option and so when the external site responds with all the scaling not set it works ok. I guess my little router box would not have coped and so set it to zero anyway.
I'll try this for a while but have a big thanks