Have spent last few days (on & off due to frustrating installing of various bits) testing this.
11g XE was installed just locally and no remote testing was performed but results were somewhat the same. Using JDBC, from Base the sign does not seem to be the problem. If an incorrect password was entered the response was almost immediate. However, if the sign on was correct it took about four minutes to retrieve anything concerning tables. During this period nothing else in LO could be performed. Nothing on the Base file which was open and could not open anything else in LO such as a Calc document. Once the process completed, most functions were normal. The same wait occurred when performing a
View->Refresh Tables or
Most time was spent trying to get ODBC connection working. Finally got working today & instant results within Oracle. However, in Base get error that it can’t find the driver.
Access from sqlplus or SQL Developer (Oracle) or even the Getting Started seem to present no problem with delays in DB access.
Have also read about older Java working on AOO 3.x. Tried Java 1.6.0_21 but no better result. Even tried in AOO 4.01 Base but again same result. One somewhat noticeable difference was openjdk was about a minute slower than Oracle JRE both in LO & AOO. Openjdk was about four minutes while Oracle 1.8.0_151 was about three minutes in each. Another weird point in LO only was about halfway through the wait, tasks area of Base went blank. Both LO & AOO had a core usage surge about this time but only LO went blank. When tables were displayed the tasks were also.
All testing was done with LO v18.104.22.168, AOO v4.01 on Mint 18.3 & Xubuntu 16.04. Also did some brief testing on Mint using LO v22.214.171.124.
From all this, it appears a Bug report should be filed. Don’t know where exactly the problem lies but there seems to be multiple problems involved and probably goes back to Open Office or even prior.