Upgrading from 11.4.1 HF2 or HF4 to 11.5.1 or 11.5.1 HF2 seems to break DNS/Routing issue

We have experienced 2 bugs along with trying to patch the open vulnerabilities in the current version of software we are running on our BIG-IP 6900 APM boxes. We have a Pre-PROD 6900 test box with identical configuration as the PROD boxes and always upgrade and test prior to installing in PROD. After upgrading the test box to from BIG-IP 11.4.1 Build 635.103 Engineering Hotfix HF2 to 11.5.1 HF2 we can connect to the VS, Authentication/Access Policy works correctly and SSL tunnel/Network access is created, but after connecting we can no longer RDP, resolve hostnames, connect to mapped drives etc. either by hostname or IP. We can upgrade to BIG-IP 11.4.1 HF4 with no issues but not up to 11.5.1 with or without applying HF's. We have been working with F5 Engineering support ran several traces, compared cinfigurations after upgrading, but cannot find why we have experienced the issues. Troubleshooting continues. Anyone else having similar issues upgrading to 11.5.1?

Bugs we have encountered and required work around until we can upgrade: 1st Bug: Service Request C1594764, the bug ID associated with your issue is ID427409. Unfortunately, the bug ID does not exist in the release notes for 11.5 or 11.5.1. However, F5 Engineer verified with a senior-engineer that the ID/bug is corrected in 11.5.

2nd Bug: Service Request C1596861, bug ID 435329 - [APM] layered VS created/modified by AAA Server, may re-use loopback ip address that is already in use by other AAA Server