Comcast Business Support Community

Comcast blocking DNS queries (UDP port 53) from my installation?

My commercial account was recently upgraded to another plan. I have static IPs and servers at this location. Unfortunately, after this upgrade, all DNS queries fail because traffic using UDP port 53 is somehow blocked. I tried querying various nameservers, such as 8.8.8.8 (Google) and 75.75.75.75 (

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Comcast blocking DNS queries (UDP port 53) from my installation?

My commercial account was recently upgraded to another plan. I have static IPs and servers at this location. Unfortunately, after this upgrade, all DNS queries fail because traffic using UDP port 53 is somehow blocked. I tried querying various nameservers, such as 8.8.8.8 (Google) and 75.75.75.75 (

If you have Security Edge enabled, Comcast will intercept, and in some cases block, DNS queries even if you use non Comcast DNS servers. Try to disable Security Edge if you have it enabled.

Non-Delivery of email from our server on a Comcast Business IP

The entire Comcast Business network (96.64.0.0/11) is listed on UCEPROTECTL2 and other ISPs are blocking our legit email even though our mail server IP has never been individually listed. Our employees are not getting important messages sent through the SMTP to SMS gateway, and this is alienating n

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Non-Delivery of email from our server on a Comcast Business IP

The entire Comcast Business network (96.64.0.0/11) is listed on UCEPROTECTL2 and other ISPs are blocking our legit email even though our mail server IP has never been individually listed. Our employees are not getting important messages sent through the SMTP to SMS gateway, and this is alienating n

E-mail delivery has become more and more of a hassle in general, not just for Comcast customers. I have been running a mail server "forever" from my business Comcast account and I am also in a UCE-listed block (70.88.0.0/14). Here are a few tricks th

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time to upgrade biz service we pay the most and get the least

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No more static IPv6 (now official?)

I just got a new modem last week (lightning strike), and noticed that I got a complete new IPv6 prefix. My static IPv4 addresses are still in place. Also, my account no longer lists any static IPv6 addresses. Is it now official that there are no static IPv6 addresses for business accounts? I know th

the post suggests that the prefix assigned by Comcast to my cable modem should be static. Is that correct?

No more static IPv6 (now official?)

I just got a new modem last week (lightning strike), and noticed that I got a complete new IPv6 prefix. My static IPv4 addresses are still in place. Also, my account no longer lists any static IPv6 addresses. Is it now official that there are no static IPv6 addresses for business accounts? I know th

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No more static IPv6 (now official?)

I just got a new modem last week (lightning strike), and noticed that I got a complete new IPv6 prefix. My static IPv4 addresses are still in place. Also, my account no longer lists any static IPv6 addresses. Is it now official that there are no static IPv6 addresses for business accounts? I know th

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IPv6 Configuration with single static IPv4 address or dynamic IPv4 address

What IPv6 configuration does Comcast currently offer if you are using a single static IPv4 address, or a dynamic IPv4 address. Currently, I do have a static IPv4 /29 (5 IP addresses), and I am getting a /56 to the modem (/59 to my firewall from the modem) in IPv6. Thinking about saving some money, b

Thanks! That page is helpful.

Hi there, @flybynight! That's a good questions and we do offer both static and dynamic and this handy overview will help you see how everything is able to work together! https://comca.st/3v14VU4 I hope this helps! Let me know if you have any ques

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