I have the following server connection setup

my linux server <=== mtu 1500 link ===> Router <=== VPN link mtu 1450 ===> Internet

Visitors who access my site if their MSS is greater than 1410 trigger PMTUD mechanism (icmp unreachable messages are sent from the router to my server)

I can use the iptables TCPMSS rule on the server and set the MSS value of SYN packets from visitors to server to 1410.

If I do this, then the PMTUD mechanism will start working for visitors that originally stated that they support MSS for example 1360, but I set it to 1410

So some part of clients will still work using PMTUD, is any way to fix mss for visitors with mss greater than 1410?

PS: I have no ability to change mtu on server-router link.