I am losing access ro the Internet when my PC sleeps awhile but only on Ethernet connected to Xfinity router

Windows 11 with a Realtek NIC, ethernet connected to Xfinity router (no other router n between0>  When my PC sleeps a long tim,e (hours), I lose access to the Internet through my web browsers.  All DNS lookups hang.  NSLOOKUP command does not work.  The only fix is to reboot the PC.  I tried eery PC solution I can think.  Updating windows to latest release, updating NIC driver to latest version.  Nothing helps.  I seen this problem a year ago and it went away for almost a year.  Could the Xfinity router be blocking DNS queries for some reason?