Internet works on Ethernet cable but not Wifi

Hello, I am sorry if I sound stupid and if I am using an incorrect prefix or anything but I have had this issue for a month and have found no solution. Whenever I am on the wifi it will randomly not work but still say I am connected to the wifi. It will also screw up any one else on the wifi. I have to disconnect and reconnect to fix this issue temporarly. When ever I am connected through the Ethernet cable it works 100%. I purchased an MSI GE 72 Apache Pro 003 (laptop). I have called support many times but they haven't found an answer. I returned the laptop and got a new one and the problem still happens so I know for a fact it isn't the computers malfunction. I have updated drivers and that has not solved this issue. It has something to do with my router or something with the ip on my laptop ( I don't remember what could effect it but I heard it in computer repair class ) I would appreciate help and if you want any information go ahead and ask. Sorry if I sound stupid or anything. I am just extremely frustrated with this.
 
Log into the router itself and report the version of the firmware on it now please
 
OK, that's the current version alright. Login, access the WAN side config, and set MTU to 1492
 
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