My vacuum cleaner won't connect to the network...

I've bought a S40 vacuum cleaner and even though I initially set it up with ease, it got disconnected from the network and I just can't seem to make it work again. I've tried the following steps to no avail:

• Reset my router
• Set my WiFi to 2,4GHz (instead of 5GHz)
• Factory reset my S40
• Long press the home and power buttons to reset the network settings.

The process always stops at around 50% when the prompt goes "Couldn't connect to the network. Please check and try again".

I would be super grateful if anyone has a solution. Thank you!