I found a similar thread here which mentions the cause and solution, but i want to elaborate some more so that you can fix it yourself if the thread is not clear enough for you. The Problem exists here if you created your Exchange LB while using the Kemp Templates (you need to login to download/access them), it created this content rule;

You can safely delete this, because the root redirection to owa is already in place in the SubVS;

After that the RCA should run without errors, i would recommend to test the redirection of OWA after that.

For reference, this problem existed on;
– Kemp Free, VLM5000 (in trial mode) and VLM200.  version 7.1-30-75.20150929-3018 and 7.1-26
– Service templates version 1.9 and 1.7.122

– Exchange 2013 with CU2/CU4/CU10 and Exchange 2016

And if you ran into this issue, you probably want to read this too;
– OWA does not work after Load balancing Exchange 2016 while using Kemp LoadBalancers
– Exchange 2013 Post SP1 with Kemp LoadBalancers exRCA ActiveSync error: operation timed out