Check the quality of the signal source First of all, you need to check the quality of the connected WiFi signal source. If the signal source is too far away or the signal quality is poor, then the WiFi signal of the phone will be affected. At this point, you can move near the signal source, or change the signal source to solve the problem.
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If the quality of the signal source is normal, but the WiFi signal of the OPPO phone is still not good, then you may need to check whether there is a problem with the mobile phone system. Try upgrading or resetting your phone's system to fix the problem. You are advised to back up data before performing this operation.
Should be the reason of the router, you can consider replacing a new router. This is because the router is used for too long, and the signal aging will cause the signal of the mobile phone to be unstable and always broken, so it should be changed in time
You can reset the phone to restore factory Settings, you can also check the phone butler