Websites become unavailable after traceroute

For the last few months I have had certain related websites becoming unavailable periodically, then becoming available again without me doing anything.

While testing I discovered that running a traceroute on any one of the misbehaving urls can actually trigger the problem, and rebooting the router always fixes it. I have disabled all scanning and filtering but this didn't help.

The problematic urls are xojo.com, blog.xojo.com, docs.xojo.com, forum.xojo.com and forums.realsoftware.com

e.g.

C:\>tracert docs.xojo.com

Tracing route to docs.xojo.com [174.138.40.53]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.0.254
  2     2 ms     2 ms     2 ms  14-200-241-121.tpgi.com.au [14.200.241.121]
  3     9 ms     7 ms     7 ms  203.29.134-3.tpgi.com.au [203.29.134.3]
  4   157 ms   157 ms   166 ms  100ge13-1.core1.sjc1.he.net [216.218.139.233]
  5   428 ms   250 ms   157 ms  100ge1-1.core1.sjc2.he.net [184.105.65.114]
  6   227 ms   224 ms   223 ms  100ge10-2.core1.nyc4.he.net [184.105.81.214]
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9   226 ms   219 ms   219 ms  174.138.40.53

Trace complete.

 

Then, seconds later

C:\>tracert docs.xojo.com

Tracing route to docs.xojo.com [174.138.40.53]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.0.254
  2     2 ms     2 ms     2 ms  14-200-241-121.tpgi.com.au [14.200.241.121]
  3     4 ms     7 ms     7 ms  203.29.134-3.tpgi.com.au [203.29.134.3]
  4   181 ms   157 ms   157 ms  100ge13-1.core1.sjc1.he.net [216.218.139.233]
  5   157 ms   157 ms   157 ms  100ge1-1.core1.sjc2.he.net [184.105.65.114]
  6   222 ms   224 ms   224 ms  100ge10-2.core1.nyc4.he.net [184.105.81.214]
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9     *        *        *     Request timed out.
 10     *        *        *     Request timed out.
 11     *        *        *     Request timed out.
 12     *        *        *     Request timed out.
 13     *        *        *     Request timed out.
 14     *        *        *     Request timed out.
 15     *        *        *     Request timed out.
 16     *        *        *     Request timed out.
 17     *        *        *     Request timed out.
 18     *        *        *     Request timed out.
 19     *        *        *     Request timed out.
 20     *        *        *     Request timed out.
 21     *        *        *     Request timed out.
 22     *        *        *     Request timed out.
 23     *        *        *     Request timed out.
 24     *        *        *     Request timed out.
 25     *        *        *     Request timed out.
 26     *        *        *     Request timed out.
 27     *        *        *     Request timed out.
 28     *        *        *     Request timed out.
 29     *        *        *     Request timed out.
 30     *        *        *     Request timed out.

Trace complete.

I don't even know where to start with this.

XG125w (SFOS 17.0.3 MR-3)