hello,
i have stable internet connection, when i run vpn to access pubg game, the connection become unstable my the not open
.
i created my own cloud vpn using routeros
l2tp
openvpn
ikev2
sstp
all kinds not stable
how my isp do that and what should I do?

the connection become unstable my the not open

Please translate what exactly means "unstable". To me, "unstable" means that it sometimes works and sometimes doesn't, or that the speed is changing.

i created my own cloud vpn using routeros

So if I understand properly, the VPN server is not one of the publicly provided services, so the ISP cannot find out by its IP address, correct?

how my isp do that and what should I do?

One possibility is that the ISP recognizes traffic patterns - all of the VPNs you've named use particular ports, and even if you change them, which is possible to do with your own VPN server, the traffic characteristics can still be recognized, although it requires some extra effort at ISP side.

But are you sure it is the ISP that makes things fail? Maybe it is just a MTU issue that needs to be addressed? Which brings us back to the explanation of what "unstable" actually means.

Please translate what exactly means "unstable". To me, "unstable" means that it sometimes works and sometimes doesn't, or that the speed is changing.

.
i mean with unstable (elevated ping, Frequent VPN disconnection, even sometime can't connect).
and sometimes work fine best ping with no problem.
the problem increase with some isp ips range

So if I understand properly, the VPN server is not one of the publicly provided services, so the ISP cannot find out by its IP address, correct?

.
yes i buy my own sever and install CHR routerOS
.

One possibility is that the ISP recognizes traffic patterns - all of the VPNs you've named use particular ports, and even if you change them, which is possible to do with your own VPN server, the traffic characteristics can still be recognized, although it requires some extra effort at ISP side.

i use l2tp, ikev2, openvpn, i prefer udp port for best ping(lower than 60ms in online game).
i tried to change port with openvpn the default one 1194 lower ping
in time my server have a problem may found some vpn server work without any problem

But are you sure it is the ISP that makes things fail? Maybe it is just a MTU issue that needs to be addressed? Which brings us back to the explanation of what "unstable" actually means.

what should i do with mtu?
adsl router with default mtu 1480
and why the problem appears with problem?
openvpn with default mtu in server side 1500
.
is mtu problems?!
or is there any vpn server setting problem?
or my server provider (Microsoft)?
or DPI (deep packet inspection) from isp?

i mean with unstable (elevated ping, Frequent VPN disconnection, even sometime can't connect).
and sometimes work fine best ping with no problem.

OK, so indeed intermittent problems.

the problem increase with some isp ips range

You mean depending on what address you get from your local ISP?

i prefer udp port for best ping(lower than 60ms in online game).

Good. But since you mention OpenVPN and UDP at the same time, do I get it right that both your Mikrotiks (the CHR in Microsoft hosting and the one at your home) run RouterOS 7? What is the model of your Mikrotik at home?

in time my server have a problem may found some vpn server work without any problem

That might indicate a network problem between your home and the datacenter where your CHR is running, or with the CHR itself. But it may also be something else.

what should i do with mtu?
adsl router with default mtu 1480
and why the problem appears with problem?
openvpn with default mtu in server side 1500
.
is mtu problems?!
or is there any vpn server setting problem?
or my server provider (Microsoft)?
or DPI (deep packet inspection) from isp?

If even pings are affected by the instability, it is not an MTU problem.

For starters, I'd say try to ping the CHR public address from one window, and simultaneously ping its internal address via the tunnel from another window, and compare the results. If the pinging of the public IP is flawless while the pinging of the private IP is affected, it is not a network problem but a VPN one.