Network has almost no wifi despite router performing as expected
I have a network of 4 Deco M5s which was working fine up until yesterday and now they have all but stopped outputting any usable speed. I have checked my router speed which is around 150mb/s and is working as normal yet I have no wifi via the mesh network. The app still says "Everything looks good." suggesting the network is active but not outputting and usable wifi. I have tried all of the troubleshooting steps such as disabling the QoS, turning off the NAT features, changing the network type all to no avail.
Please inform me what more information you require in order to diagnose this issue. A prompt response will be appreciated as we are two professionals working from home and are completely reliant on this network.