As the title explains i can connect via my Windows 10 to my Router Via. L2TP without any problems.
i then tried to ping some ip's i know i have devices on. but no avail.
im runnig a clean config with l2tp. very new to this so if you need any setup please tell me which commands i need to use. thanks! looking forward to a good response
the site i got the guide from: https://wiki.mikrotik.com/wiki/Manual:Interface/L2TP
if this guide is somehow wrong please tell me and maube point me to the right spot for correct setup advice. Thanks!

it depends in your OS. Just add you remote LAN network to you routing table.

That is typical situation when you forget to add arp=proxy-arp to your LAN interface. It happens because your computer gets local address via VPN, but it is not on the same L2 segment so when other devices from LAN try to reply, they can't find your computer's MAC and therefore they can't reply. By setting proxy-arp, router will answer those ARP requests and forward packets back to you.

If that is not the case, you might also have incorrect setting with your IP and it would be easier to spot the mistake, if you share your config (/export hide-sensitive). Don't forget to find&replace any personal information.

Personally I don't think that adding route into your OS will change something - the route should get dynamically created once you connect to VPN and your ability to ping router proves that windows know how to reach the IP