@Clive_A That much is clear indeed. But why didn't my switch accept it as a value? Does the 64 prefix imply a limited set of starting digits in the IP address (like the different scopes and subnets...

@Clive_A OMG! That did it indeed :o Could you explain me why, please?

@Clive_A

@Clive_A If I input the entire local IPv6 address of my router (which should be the default Gateway) the frontend doesn't allow it. If I remove the / the frontend accepts it, but then comes back with...

I'm trying to add a default IPv6 route to my switch, however it keeps failing on the IP address for some reason. Any ideas as why this could be failing, please? Or how I should go about setting this...

Found and solved the issue! For some reason the IP address for my gateway (router) was saved into the Primary DNS, and thus no gateway address was set. Just blanked the Primary Address and moved it...