# Use static network ports for adding a second device **URL:** \ **Category:** Feature Proposal\ **Created:** [March 25, 2026, 9:01am UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956 "2026-03-25T09:01:13Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Dio](https://support.delta.chat/user_avatar/support.delta.chat/dio/32/1122_2.png) [@Dio](https://support.delta.chat/u/Dio)\ **Post date:** [March 25, 2026, 9:01am UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/1 "2026-03-25T09:01:13Z")
While trying Deltachat for small/medium business use I came across the following issue: desktops and mobile phones are in different VLANs. Traffic between VLANs passes a router/firewall, which only allows specific connections. See also this thread: [Add second device: which network connections are made?](https://support.delta.chat/t/add-second-device-which-network-connections-are-made/4619) ## Expected behavior I need to allow inter VLAN connections in the firewall to Deltachat destination ports, so that mobile phones can be added as second device to existing desktop clients. ## Actual behavior When adding a second device Deltachat choses a random network port for the incoming connection. I cannot allow a random port in the firewall. ## Solution Deltachat should try some static ports for incoming connections first. If those ports are already in use by other tools, use a random port. Examples: 1. try port 62009 first, then random: a single port is more likely to be already occupied, so… 2. try ports 62009-620011 first, then random. Easy to configure in firewall. 3. try ports 62009, 63009, 64009 first, then random. Probably the highest chance to get a free static port. Falling back to random port makes sure it will always work for the home user just like before. ---
**Author:** ![Minim](https://support.delta.chat/letter_avatar_proxy/v4/letter/m/ccd318/32.png) [@Minim](https://support.delta.chat/u/Minim)\ **Post date:** [March 30, 2026, 2:15pm UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/2 "2026-03-30T14:15:09Z")
Is there any case for trying a set port in amongst some random ones, to avoid fingerprinting? IRL people will add contacts over dodgy LANs. ---
**Author:** ![Dio](https://support.delta.chat/user_avatar/support.delta.chat/dio/32/1122_2.png) [@Dio](https://support.delta.chat/u/Dio)\ **Post date:** [March 30, 2026, 2:48pm UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/3 "2026-03-30T14:48:19Z")
Hi, what do you mean by fingerprinting here? The dodgy LAN owner can recognize that you are probably using Deltachat? Is it a good idea to add second devices on untrusted LANs? Is the connection encrypted and authenticated? ---
**Author:** ![Minim](https://support.delta.chat/letter_avatar_proxy/v4/letter/m/ccd318/32.png) [@Minim](https://support.delta.chat/u/Minim)\ **Post date:** [March 30, 2026, 2:54pm UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/4 "2026-03-30T14:54:48Z")
Yes, some countries block traffic that is recognisably from tools they ban, and they may require that private individuals implement such censoring configs. At the extreme, Russia restricts use of non-whitelisted mailservers! The connection is encrypted but I don’t think that would hide the port. 🙂 ---
**Author:** ![Dio](https://support.delta.chat/user_avatar/support.delta.chat/dio/32/1122_2.png) [@Dio](https://support.delta.chat/u/Dio)\ **Post date:** [March 30, 2026, 4:54pm UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/5 "2026-03-30T16:54:03Z")
I don’t see how this is related to the "add second device” function 🙄 ---
**Author:** ![Minim](https://support.delta.chat/letter_avatar_proxy/v4/letter/m/ccd318/32.png) [@Minim](https://support.delta.chat/u/Minim)\ **Post date:** [March 31, 2026, 6:01pm UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/6 "2026-03-31T18:01:08Z")
Fair, I was thinking that a similar setup might be used for adding contacts, without reason. Adding a second device onwan adversary-configured network would be a rarer concern. ---
**Author:** ![Dio](https://support.delta.chat/user_avatar/support.delta.chat/dio/32/1122_2.png) [@Dio](https://support.delta.chat/u/Dio)\ **Post date:** [October 2, 2026, 10:45am UTC](https://support.delta.chat/t/use-static-network-ports-for-adding-a-second-device/4956/7 "2026-10-02T10:45:19Z")
Just wanted to push this up again.