It's hard to see what difference the adaptor would make provided it's making a sound connection. Same with the fuse. Check it's ok and not corroded in any way.

Local emissions regulations do differ as well, not just the rules for what the plug is supposed to be like. Just don't.

The UK and Spain are both in the EU. People move around the EU and bring in adaptors of all kinds. It's necessary and not illegal or in contravention of regulations as suggested. Indeed, it is very likely that such devices conform to EU standards.If it were me, I'd use the utility to reset it and see how that goes.

Powerline adapters are a special case, for they have intended emissions (the powerline frequency spectrum) right across the aerial radio spectrum - their range is 2~68 or 2~86 MHz.

Radio frequency usage does differ from country to country, particularly for things like emergency services and police. This is why country specific PLC firmware exists - each one is configured to exclude certain frequencies from PLC usage.

When I visit the firmware download there is no choice of country. There wasn't even any documentation includee regarding emissions when I bought the A600s.