PortServer TS number of sessions problem

We have detected when we have more than 8 SSH sessions the PortServer TS-1 start collapsing. We cannot access to the device and serialoverip behavior degrades affecting to the final equipment.

From the firmware release notes:

Some modern TLS/SSL-based clients and/or servers require a more
secure mechanism to exchange security information than was supported in
this product. The strength of the “Diffie-Hellman Group” has been
doubled to improve compatibility with modern systems, at the potential
cost of performance. See known limitations.

KNOWN LIMITATIONS

- This firmware version updates and restricts encryption to the device
  according to recent industry guidance and best practices.  Given the
  resource constraints in this product architecture, and the increased
  computational power required to implement newer encryption methods,
  these latest changes may impact product performance in some
  applications, significantly increasing the time required for encrypted
  communications to complete.  If application performance with this
  revision is not suitable, the best options are to revert to the
  previous (revision W) firmware or use the product without using
  SSL/TLS encryption.