Problems connecting after power outage

I have problems which occur each time the comcast network recovers from a power outage. My work and home computers and mobile phones (via wifi) work fine but my roku devices won't connect and samsung tablets can get to some websites but not others. After several days, the problems resolve.

Just now I'm concentrating on one website, bibliocommons.com. Both windows computers and my iphone can get to it okay: From my desktop:

Tracing route to bibliocommons.com [198.49.23.145]

over a maximum of 30 hops:

1 6 ms 6 ms 6 ms 10.0.0.1

2 22 ms 14 ms 16 ms 96.120.90.145

3 16 ms 16 ms 17 ms 68.86.249.113

4 18 ms 26 ms 35 ms be-214-rar01.santaclara.ca.sfba.comcast.net [162.151.78.93]

5 19 ms 20 ms 18 ms be-39931-cs03.sunnyvale.ca.ibone.comcast.net [96.110.41.121]

6 19 ms 18 ms 18 ms be-3302-pe02.529bryant.ca.ibone.comcast.net [96.110.41.218]

7 16 ms 16 ms 18 ms ix-xe-0-1-1-0.tcore1.pdi-paloalto.as6453.net [66.198.127.33]

8 20 ms 20 ms 18 ms if-ae-2-2.tcore2.pdi-paloalto.as6453.net [66.198.127.2]

9 21 ms 32 ms 19 ms if-ae-5-2.tcore2.sqn-sanjose.as6453.net [64.86.21.1]

10 16 ms 17 ms 18 ms if-ae-1-2.tcore1.sqn-sanjose.as6453.net [63.243.205.1]

11 19 ms 19 ms 18 ms 63.243.205.62

12 29 ms 31 ms 18 ms po111.bs-b.sech-sjc.netarch.akamai.com [209.200.184.202]

13 * * * Request timed out.

14 22 ms 21 ms 19 ms ae121.access-a.sech-sjc.netarch.akamai.com [209.200.184.205]

15 86 ms 86 ms 84 ms a72-52-43-164.deploy.static.akamaitechnologies.com [72.52.43.164]

16 84 ms 86 ms 83 ms 198.49.23.145

When I try pinging the address from the tablet it times out. On other networks this doesn’t happen. If I drive to where I have cellular connection and hot spot to the phone, it works correctly.

Comcast has so far sent me a new gateway. However, since activation seems to require an internet connection and I have cellular data service, I gave up. I’ve changed the secondary dns server on the table to google, however the gateway is set to comcast.75.75.75.75 and 75.75.75.76 and I don’t see a way to change from either the admin tool or xfinity app.

I know these are comcast network problems - what more data can I provide to help them identify and resolve?

Thanks in advance!