Since both of you suggested it might be an issue because of double-NAT, i've taken the risk of the lady of the house leaving me and my children no longer recognizing me a a father... aka risk losing internet connection in the house... I had my ISP put the modem in bridge modus.
The fact that i am able to respond here means I survived and that that indeed solved the problem!
I am still a bit confused here, since i couldn't find
anything in
any log. But like
@anodos said, probably an issue with the modem in that area. Which is still akward, since i had other WiFi routers behind it doing NAT before and never had any issues with those. Sigh... Network troubleshooting is hard sometimes. Does make me respect the "IT Guys" from the office more :p
Thanks for your both responses
@anodos and
@Jailer (also on the pfSense forum ;) )