Can't save new port forwarding rule

[turboxjp]

I'm trying to set up a new port forwarding rule for a gaming server, but the hub manager does not let me save the new rule. Instead of adding a rule to the list, it simply refreshes the page when I click 'save' and resets the page. The same thing happens when trying to change any configuration settings such as turning off PnP.

Any help would be great!

[turboxjp]

Just adding to this quickly, I have my pc connected via ethernet to a range extender (tp-link, not BT!) - if this could be the issue then let me know!