Outlook SharePoint Calender’s sync is not working with SharePoint 2013

I have created a Calendar list added the event in the Calendar. And connect to outlook. Calendar is showing events on the outlook only for first time. But the events are not showing with from the outlook created events on SharePoint and the events is not showing which are created from SharePoint 2013 list.

Below error are showing on a popup Outlook send/receive progress error

Task ‘SharePoint’ reported error (0x80040102) : ‘Outlook cannot connect to the SharePoint List (DevSmart – EventCalendar). The server may not be reachable from your location. Contact the SharePoint site administrator for more information. HTTP 400.’

I tried to resolve from outlook SharePoint Lists, double click on the check box “Display this list on the other computers with the account”.

Is there any way to resolve this this?

Connect Sharepoint calenders to outlook, can we modify the sharepoint calender from outlook

I have a sub-site inside a sharepoint on-premises 2013 team site, and i have enabled the “Offline Synchronization for External Lists” site feature. now from the sharepoint calendar >> I click on “Connect to outlook” , as follow:-

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and i got the calendar inside my out look, as follow:-

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but the issue is that i am unable to modify the sharepoint calendar from my outlook, as when hover over a date inside outlook, i did not get the “+ ADD” link. also when i did the connect >> i got this dialog which mentioned that my permission will be Read on the calendar (so is this related to my issue that i can not modify the sharepoint calendar from my outlook):- enter image description here