I don't believe that the LG G6 has the correct band support for the AWS network that Shaw/Freedom uses.
This means that you will not get it to connect to their main Network, only Nationwide (Rogers/Telus/Bell)
@Techjunkie -- I don't believe that the LG G6 has the correct band support
For "LG" devices, I do believe that Shaw Mobile's "bring your own phone" device compatibility web-page lists:
Model Name | Model Number | WiFi Calling | VoLTE | Extended Range LTE
G6 | H873 | ✓ | ✓ | ✓
All jokes aside, I believe you have to do a factory reset with the new SIM card in on LG devices for it to load the config when you use it on a different carrier.
I would try that (back up your stuff first).
I had the exact same problem as yours. one of my phones keeps showing nationwide even we are in the city area. I even went to Shaw for changing the sim but still no luck So I contacted the tech support and they told me that because Shaw signal in that area is not as strong as another provider so it tends to take other networks instead. btw, What I did was go to Settings--> Mobile network --> Manual select network --> select Shaw. After that, it stops roaming me to nationwide but one in a while it would show no signal in my area.
Sorry had difficulties with my access to the site. After countless hours with Shaw support online, the issue was resolved in under a minute by the rep at the Mobile Shop in Superstore. Although LG G6 is listed as supported device but it happens that there are different versions of G6 and the only the H873 is supported. My G6 is a 870 and doesn't support the GSM network that Shaw uses (he explained but I didn't quite understand). So I need to buy a new phone. Case closed. Thanks everyone for your input.