Ring Doorbell Delay Notification To Phone

I'm very pleased with my Ring Doorbell but there does seem to be a significant delay between the doorbell being pressed and my phone receiving a notification by which time the caller may have left. I note that the Wifi signal varies between 59 and 65 which may be the cause. I tried a TP Wifi booster and extender but it did not improve the signal strength. Any ideas what to try next? My son has suggested as we have an ethernet point downstairs we could use a wireless access point and a Injector POE.