Comment 38 for bug 1788997

I think this commit should fix the bug:
af8a41cccf8f rtlwifi: cleanup 8723be ant_sel definition

However, this commit was added to Bionic in 4.15.0-33, which I believe you already tested. Can you test -proposed or newer than -33 to see if this bug is fixed? If not, there is only one other rtl commit in v4.17-rc4.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed.

Thank you in advance!