My Network works except one link


i have a zerotier network an everything seams working excepting that one link connection does not working.
What is one link — the network has the internal ip and i could ping every “online” host within this network but there are two ips/hosts:


which can’t ping or transfer any data between.

These are both mikrotik routers and i could reach every other hosts from these to hosts.
Any Ideas how to “debug” this problem?

thx in advance