Problem Accessing Certain Websites

My apology for the long explanation of my Issue.

I've been able to connect to "now problem websites" for the past 30 yrs since being customer with Comcast/Xfinity.  About 4 wks ago, I was unable to access certain websites -- Connection timed out.  These sites are very important to me --dealing with my Veteran health, Army-retirement pay; medical health & medications.

I called customer support -- talked with tech level I & II (after so many "dropped calls).  I told them that it was not just my computer by all computers.  It was not websites since I was able to access them using my cellphone hotspot connection.  I tried using VPN --- it connected fine but unable to authenticate to get in.  Tech II said that my Xfinity gateway was not up to date -- setup appointment for technician to come & replace it with up-to-date Modem (XB8).  Technician try to resolved problem using the old Modem -- unsuccessful.  After replacing with updated modem & getting "New IP Address" from DHCP server, I was able to connected to problem sites -- problem solved.

Yesterday (4 May 2025) problem returned -- connection timed out to same websites.  Talked with technical support and after 2 hrs, I was told that all diagnostics & solutions has been applied and to wait 2 hrs then try to access website.  I asked if I could get new IP address from Xfinity DHCP server since that seems to solved the issue.  I was told to just wait for the 2 hrs to pass and to have faith in the solution.  After 2 hrs passed, the problem still exist.

I received text message for feedback to rate -- I reply with "2" since problem was not resolved.  I received call from quality control -- explained the reasons.  She tried to get me connect with technical support. After waiting about 20-30 mins, I got connected.  The person asked what's the problem -- I gave her update.  She told me that she dealing with internet connection problem and not websites problem -- not allow to access websites.  I explained to her that I'm not asking her to access but that I'm having issues connection to websites.  She forwarded my call to "Advance Tech Support".  Once connected, received recorded message that it was after regular hours -- to called back.

This is so very frustrating -- I know I'll have to go to the same cycle of explain everything to a new tech support and may or may not get problem resolved.  I know I can connect to websites using my Cellphone Hotspot but I feel that I shouldn't have to since I do have Xfinity unlimited high speed connection.

If anyone have ideas or can assist, please do so.  As stated, these website are very important to me as a dedicated Veteran and so far -- a loyal Comcast/Xfinity customer for 30 yrs.