Hello! This is my first post on this forum, hopefully I get a quick reply

So basically my TP link router is connected to the main router, the purpose of using this TP Link router is to make an L2TP connection to my vpn server so that the wifi given out by tp link is basically the vpn wifi and all users of my tp link wifi automatically get connected to that server. 

Back to the issue, all goes well the server works fine but I hit one bump and that is after like 12-13 hours the tp link router automatically gets disconnected from the server and I have to manually go back to the router interface and select disconnect and connect again and all goes up and well and this cycle repeats. 

My question is why is it getting automatically disconnected and not connecting back again?

Points to note: 

I've ensured that the connection is set to automatic so it gets connected automatically

The time zone of the l2tp server is different from the timezone of my main isp internet, do I need to match the timezone of my tp link router to the timezone of the l2tp server I've connected it to? is that why its happening? Or what are the other probable causes? Please HELP!

I've checked the server it works pretty fine so I'm sure the issue lies withing router settings.