A router is a machine that is connected to more than one network and forwards traffic between connected networks.
Are there any routers in RedeA? Are there any routers in RedeB? (We don't count your server, because it is connected at most to RedeA and RedeB.)
Link-local routes appear quite automatically. The default route is due to config.
You have repeated that phrase several times. What does it mean? What is "source traffic"?
You have repeated that phrase several times. What does it mean?
Those rules are easy:
Allow access to port tcp/22 (ssh) from networks 192.168.0.64/26 and 192.168.1.0/24
That is more strict than the default of allowing to tcp/22 from anywhere.
Furthermore, we don't even know where those networks are. We should not need to care about that, but if you restrict ssh access now, then you cannot ssh into the server at all.
The service iptables is enabled. If the machine really has 0 rules (or the rules added by you) after reboot, then you have wiped out the default rules.
That would be ok, if you would know that you don't need them and that the rules you add are proper. You don't.
Admittedly UFW or similar could protect you from some mistakes, but they can't resolve your basic network configuration errors.
It would be really good if you could hire professional help.