Thanks jaclaz, Comparing the fan options for the CRS310 looks like Arctic S4028 is a possible good option, Also switching to RouterOS appears to be a general safer option. My setup is 3 seperated vlans and a trunk port link.
Can I back-up the config on SwitchOS (.swb backup file) and restore the .swb backup file in RouterOS OR would I need to rebuild from scratch the config in RouterOS?
Unfortunately you need to rebuild from scratch on RouterOS, but if you take some notes/screenshots of your current SwOS setup It shouldn't be that much difficult.
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The steps seem simple enough: try ROS; if it is not sufficient then get a more powerful fan.
I use the Noctua in my CRS310, which is not fully populated (no SFP). I also run ROS for better control. In this situation the fan is more than adequate.
In the OP configuration the DAC should be not an issue, the RJ45 SFP might.
This Is why I would try reversing the Noctua fan as a test.
Besides the (usually slightly more efficient) effect of blowing fresh air over the heatsinks when compared to extracting the heated air, the way the device Is setup the fan blowing outwards implies that the air already heated by the SFP Is drawn across the heatsinks.
In any case trying It costs nothing.
Thank you jaclaz,
I have flipped the fan to instead intake external air which blows air over the mboard and ports.
However the recreation of vlans is now an issue in RouterOS vs SwitchOS, my previous vlan configuration in SwitchOS looked like this and worked ok:
Previous VLAN tab in SwitchOS:
Previous VLAN"s" tab in SwitchOS:
Now below trying to recreate VLANs in RouterOS, but im getting no joy in getting these vlans working again. What do I need to do to get these vlans working again??
Post an export of the configuration, instead of the screenshots for RouterOS, instructions here:
Sure below switch config export:
# 2026-01-29 01:28:05 by RouterOS 7.21.2
# software id = XXX-XXX
#
# model = CRS310-8G+2S+
# serial number = XXXXXXXXXX
/interface bridge
add admin-mac=XX:XX:XX:XX:XX:XX auto-mac=no comment=defconf name=bridge
/interface vlan
add interface=bridge l3-hw-offloading=no name=99 vlan-id=99
add interface=bridge l3-hw-offloading=no name=100 vlan-id=100
add interface=bridge l3-hw-offloading=no name=200 vlan-id=200
add interface=bridge l3-hw-offloading=no name=300 vlan-id=300
/interface bridge port
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether1 pvid=200
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether2 pvid=200
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether3 pvid=300
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether4 pvid=200
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether5 pvid=300
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether6 pvid=300
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether7 pvid=100
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=ether8 pvid=100
add bridge=bridge comment=defconf interface=sfp-sfpplus1 pvid=99
add bridge=bridge comment=defconf frame-types=\
admit-only-untagged-and-priority-tagged interface=sfp-sfpplus2 pvid=100
/interface bridge vlan
add bridge=bridge untagged=sfp-sfpplus2,ether8,ether7 vlan-ids=100
add bridge=bridge untagged=ether1,ether2,ether4 vlan-ids=200
add bridge=bridge untagged=ether3,ether5,ether6 vlan-ids=300
add bridge=bridge tagged=sfp-sfpplus1 vlan-ids=99
/ip address
add address=192.168.10.5/24 comment=defconf interface=bridge network=\
192.168.10.0
/system health settings
set fan-min-speed-percent=30% fan-target-temp=55C
/system swos
set address-acquisition-mode=static identity=MikroTik static-ip-address=\
192.168.10.5
If you can, you should take (temporarily) a port out of the bridge and VLAN's, to be used as "emergency access" in case of troubles with the VLANs settings.
At first sight what you have seems fine, but I am not an expert in VLAN settings.
What you miss, to have your setup actually do something, is to enable VLAN filtering on the bridge, i.e.:
/interface bridge
add admin-mac=XX:XX:XX:XX:XX:XX auto-mac=no comment=defconf name=bridge
should become:
/interface bridge
add admin-mac=XX:XX:XX:XX:XX:XX auto-mac=no comment=defconf name=bridge vlan-filtering=yes
I have all ports plugged and occupied and running RouterOS there is noticable fan noise with Noctuas blowing inwards, not as loud as stock fan perhaps il have to get the Arctic fan or another fan.
Also got vlans separated BUT not getting dhcp ip address from dhcp routers in each of the subnetted vlans, I think the config of trunk port is an issue, so will have to post on category RouterOS to resolve this vlan issue
You are suggesting it is louder than when the fan extracted air rather than pushing it in? Did temperatures change?
Given your fully populated box then it seems the Noctua is insufficient. There are potential disadvantages to reversing the direction from normal, to blowing in rather than out. It helps the heatsinks on which you are now immediately blowing, and heats up everything else because they (including the SFP cages) get the now pre-heated air. It will also change airflow patterns with unknown effects. I would stick with what Mikrotik designed in terms of direction, and find the best compromise between noise and effectiveness with alternative fans. I agree their factory fan is too loud outside a soundproofed enclosure. It may also help simply to pop a large finned heatsink on top of the hottest area of the case, or one that covers the whole case.
As @jaclaz said, you’re missing vlan-filtering on the bridge’s settings.
This is the config that matches your screenshots for SwitchOS:
/interface bridge vlan
add bridge=bridge vlan-ids=100 tagged=sfp-sfpplus1 untagged=sfp-sfpplus2,ether8,ether7
add bridge=bridge vlan-ids=200 tagged=sfp-sfpplus1 untagged=ether1,ether2,ether4
add bridge=bridge vlan-ids=300 tagged=sfp-sfpplus1 untagged=ether3,ether5,ether6
add bridge=bridge vlan-ids=99 untagged=sfp-sfpplus1
Also, what VLAN is your management IP for the switch? Right now it’s programmed for VLAN 1.
Generally speaking the direction of the fan should not affect noise, so maybe there is something else going on.
The forces exerted on the motor/bearing, that ultimately are what could cause abnormal noise, are due to the volume of air moved by the fan, these can only increase if the air encounters an abnormal resistance (like fan blowing into an almost sealed box), but I doubt, given the low-low amount of air moved by the Noctua fan and its low pressure, that this could be the case.
@phascogale
Reverting the fan should be an experiment, to see if anything changes in temperature, on the given reddit thread there is a thermal image taken of a CRS310, from which it seems that the (on the OP's device with a smaller heatsink) left side chip doesn't heat much:
so the air blown through and over it (that will reach the SFP cages on top left) should not be much hot.
Anyway, if it works blowing, good, if it works sucking, good, as long as it works, anything goes. 
Thanks sirbryan,
The config has been updated and now below, vlan filtering is now enabled with pvid 99:
However:
1, From Mikrotik switch (192.168.10.5) im unable to ping any hosts inside those 3 subnets ping error is: "no route to host"
2, Openwrt router (192.168.10.1 router on a stick) im unable to ping any hosts inside those 3 subnets ping error is: "Network unreachable"
I think the config issue which needs to be resolved is with the trunk port OR it could be elsewhere??
Current config:
2026-01-28 12:03:52 by RouterOS 7.21.2
model = CRS310-8G+2S+
interface bridge
add admin-mac=xx:xx:xx:xx:xx:x auto-mac=no comment=defconf name=bridge pvid=99 vlan-filtering=yes
interface vlan
add interface=bridge l3-hw-offloading=no name=99 vlan-id=99
add interface=bridge l3-hw-offloading=no name=100 vlan-id=100
add interface=bridge l3-hw-offloading=no name=200 vlan-id=200
add interface=bridge l3-hw-offloading=no name=300 vlan-id=300
interface bridge port
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether1 pvid=200
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether2 pvid=200
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether3 pvid=300
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether4 pvid=200
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether5 pvid=300
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether6 pvid=300
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether7 pvid=100
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=ether8 pvid=100
add bridge=bridge comment=defconf interface=sfp-sfpplus1 pvid=99
add bridge=bridge comment=defconf frame-types=
admit-only-untagged-and-priority-tagged interface=sfp-sfpplus2 pvid=100
interface bridge vlan
add bridge=bridge untagged=sfp-sfpplus2,ether8,ether7 vlan-ids=100
add bridge=bridge untagged=ether1,ether2,ether4 vlan-ids=200
add bridge=bridge untagged=ether3,ether5,ether6 vlan-ids=300
add bridge=bridge tagged=sfp-sfpplus1 vlan-ids=99
ip address
add address=192.168.10.5/24 comment=defconf interface=bridge network=192.168.10.0
system health settings
set fan-min-speed-percent=30% fan-target-temp=55C
system swos
set address-acquisition-mode=static identity=MikroTik static-ip-address=192.168.10.5
Which port on CRS is used to connect the openwrt router? Shown config doesn't have any trunk port carrying all VLANs ... sfp-sfpplus1 is tagged member only of VLAN 99 so you should be able to ping between CRS and openwrt on subnet 192.168.10.0/24
Well, maybe it is a copy/paste mistake, but that config does not contain what sirbryan suggested.
sfp-sfpplus1 is physically connected to the openwrt router, currenly there are no sucessful pings between CRS and Openwrt. What config do I need to apply to CRS via WinBox GUI so that the trunk port carrys all 3 vlans?
think i've made the correct changes - tag sfp-sfpplus1 to individually to all 3 vlans
Something I forgot to mention on the airflow subject: If you are equipped to turn those air exit holes into a single round hole with a clean edge then you will raise airflow while reducing noise (normal fan direction). This modest but noticeable combined improvement arises through reducing both back pressure and turbulence. Those drilled holes are cheap and easy but not very good for airflow.
No, but they do somehow prevent from large objects entering fan housing, potentially completely blocking fans. Yes, there are better alternatives (e.g. fine mesh), but generally drilled holes are just fine in most use cases. The only problem arises when one wants to use actively cooled device in a silent environment ... where passively cooled device would be more appropriate (but that comes with its own can of worms).