I'm going to assume you are using an MX68 with built in WiFi - if not, then the issue is not related to the MX68.   I have run into issues with old Brother printers not being able to connect modern WiFi because they can't support the modern crypto.   Any chance there is an old AP as well still plugged in somewhere?   Printers and IoT devices often have issues with modern protocols like 802.11r and 802.11w - so you could try dumbing the network down and turning these off on the WiFi. ... View more