If you have Telus home internet and are having problems with your wifi, you will need to get that addressed. If it is weak signal, there are boosters out there for that. If you have a T3200M gateway, turning off Smart Steering can help. Using the 2.4GHz wifi has greater range than 5GHz. If wifi is simply just dropping and affecting all wireless devices, not just a single phone, resetting the modem/gateway and setting wifi back up may be a next step. Lastly if troubleshooting fails, there is a tiny chance it could be a hardware issue and would need replacing.
If your home internet is through another provider, you'll need to contact them regarding wifi the issues.
If you have an iPhone, turning off Wi-Fi assist will stop your phone from using cellular data if Wi-Fi is weak. If Wi-Fi is non-existent, then cellular data will take over.