I'm pretty sure it's only this computer having those issues. I've also tried disabling firewall on both the router and my computer (windows firewall). The thing is i've had this problem for a while, i once contacted grinding gear games (makers of path of exile) about a problem of me not being able to connect to their instances. I've tried a bunch of things, ran some kind of diagnostic tool to find out what the problem was (didnt give a clear answer), then i tried port forwarding (which might i might not have done right) which didnt work. I even tried to use a VPN which didnt work... I mean i don't have the technical knowledge ofcourse but this seems like such a weird problem, wouldn't most connective issues prevent me from connecting at all? For instance i need to start up rocket leauge like 2-6 times before i finally connect, i need to spam click the runescape client (if i start up just 1 at a time itl just give me a connection error indefinitety) etc etc etc. Anyways, i'm rambling, i can forward those emails i exchanged with ggg to clarify what i've done to try and resolve the issue, i've also added a screenshot of my 'security' tab of my router/modem settings. I'll disabling both firewalls in the morning (its 2:30 am here right now). Thanks in advance!
Marco
EDIT: Not sure if the image was included, the 'security' tab on my router/modem setting says: SPI firewall protection: low
IPv6 firewall protection: on
Block fragmented ip packets: disabled
Block port scan detection: enabled
IP flood detection disabled
'block WAN requests' --> 'block anonymous internet requests: enabled