I'm not sure whether the cause is in radsecproxy or on Google side.
We are experiencing unstable connection for radsec.openroaming.goog using a profile generated by Pixel's built-in OSU.

The symptom is as follows.
(tested with radsecproxy 1.10.0, 1.9.3, and 1.9.2, all affected)

1. Just after invoking radsecproxy, the RadSec + DPD works well for some time.
2. After a few minutes of silence w/o request, the RADIUS packets seem being blocked. Access-Request packets won't receive any reply.
3. After some tens of minutes, the RadSec + DPD starts working well.
4. (repeat from 2)

Log file and a summary are attached. The requests between line 672-1181 are affected.
(Please ignore some lines for Samsung, etc.)

messages-0222.txt
radsecproxy-summary.txt