user88390: I run a Bitcoin node for about 1.5 months and I notice that there is no feeler connection is made in 25 days, hence the IPs in the tried table does not grow.
I also notice in the debug.log during the same period of time, many potential stale tips are detected:

2019-02-20T13:26:59Z Potential stale tip detected, will try using extra outbound peer (last tip update: 2737 seconds ago)

Does extra outbound connection when tip is stale disable feeler connection?
If yes, is it normal to have stale tip for 20+ days?

user88390: The problem is because the netgroup of the feeler connection was not properly handled. 
Check further pull requests and fixes here: https://github.com/bitcoin/bitcoin/issues/15484

88390: <p>I run a Bitcoin node for about 1.5 months and I notice that there is no feeler connection is made in 25 days, hence the IPs in the tried table does not grow.</p>

<p>I also notice in the debug.log during the same period of time, many potential stale tips are detected:</p>

<blockquote>
  <p>2019-02-20T13:26:59Z Potential stale tip detected, will try using extra outbound peer (last tip update: 2737 seconds ago)</p>
</blockquote>

<p>Does extra outbound connection when tip is stale <em>disable</em> feeler connection?
If yes, is it normal to have stale tip for 20+ days?</p>
 88390: <p>The problem is because the netgroup of the feeler connection was not properly handled. 
Check further pull requests and fixes here: <a href="https://github.com/bitcoin/bitcoin/issues/15484" rel="nofollow noreferrer">https://github.com/bitcoin/bitcoin/issues/15484</a></p>
