Setup VPN for remote access to PTP links

can someone advise how to setup access to remote aps that are not directly connected to my network?
i mounted a few ptp links that are not connected to my network, but are connected to the internet. of course they are behind ISP routers and they’re just bridges, not doing any routing.
i’d like to be able to access them remotely. i don’t have access to ISP routers, and port forward is not possible.

i can setup a vpn server on a mikrotik in my network for that on an random high-enough port like 60000.

Up till the above sentence your question made perfect sense to me.

I think a site-2-site vpn is a very nice solution and can be accomplished pretty easily. Wireguard (in case you can use RouterOS v7.x) or any other preferred VPN service when using RouterOS v6.x.

Why the requirement of the “random high-enough port”? You are aware that you can use any port you like. And you can filter by IP (perhaps even incorporate DDNS).

site to site i don’t know how to setup. pptp proved insecure and had many login attempts. i didn’t figure how to use non-standard port for pptp, it was 1723 and constantly attacked. so i turned that off.
i have ROS 6.48, longterm.
i could install v7 on router but not so sure about ptp links, they’re on v6.
i’m not so good with vpn and tunneling - i don’t want remote vpn to connect to my internal network but some random new subnet created just for that