appalling service unstable connection

My wifi router says it is connected to the network, yet not of my devices can connect to the internet. I have 7 devices that are on the Vodacom network this specific one is the only one with this issue. The Router has been replace multiple times and a sim swap has been done. Is it because the contract is question was on promotion?

I have been calling in for at least 9 months. Everyone says the same thing yet nothing get resolved.