MikroTik

I have L2TP via IPSec connection setup running on 6.46 (stable)
Scenario: user1 is connected, everything is good, as soon as user2 connects user1 can't reach the gateway and after ~1 minute gets disconnected.
user1 and user2 receives different IP's, I haven't seen errors in l2tp, ppp and route logs.
Any other ideas?

Do both users come from the same (public) IP? Then this is normal. IPSec cannot distinguish them.

Try one from a different IP, for example via WIFI tethering from your mobile phone.

Thank you Njumaen!
I didn't know about this issue with IPsec and same source IP, however I did try connecting from cellular and Wi-Fi, I had the same issue.
Then changed the DHCP pool assigned to L2TP to another one, with the new pool I don't have the multiple user/one connection working only issue anymore. I was looking for any miss-configuration with the old pool but didn't find any