Haxxio UDP Serial Port Redirector
In recent years, Wi-Fi network communications have become cheap and highly available. The suffer much less from any of the problems noted above. It is not possible to use low cost Wi-Fi Access Points to extend a network to where the serial devices are, often at a cost of less than $100 US per device.
There isn't anything special about wireless networking from the point of view of the Redirector - it requires an IP network to function, and thus is agnostic as to whether that network is wired or wireless.