F300-25 water damage

We’ve had our 2nd F300-25 back haul failure due to water getting into the ethernet port. The first had obvious moisture in the jack, the 2nd had the classic greening and burnt pins. Curious if anyone else has encountered this? We’ve had multiple instances of heavy storms with high wind driven rains as well as heavy ice event during the year plus they have been deployed.

We will be replacing it with a CSM but still have a few F300-25 back hauls out there and I’m considering sealing the covers with a thin silicon layer to try and prevent the issue. We have a third F300-25t that may be experiencing the problem as we have had several unexplained ether0 drop outs in the last two weeks and we will be climbing this weekend to check it out. That is how the most recent failure started.

We have been using F300-CSM on our latest back hauls and will be replacing the current F300-25 radio with a CSM.

May try my hand at replacing the ethernet port on the radio myself.

1 Like


Can you share MSNs of these 2 Force300-25 units?
About third F300-25, please let me know if you see water issue as well. If not or in any other case not relating to water ingress, please have then upgraded to latet 4.6.1 and see if issue of packet drops persists. Thank you.

They are all running 4.6.1. The corrosion/blackening on both units is obvious so very much doubt its a software issue, but I’ll gather the MSN.


Do your PTP ethernet cables go above the F300-25 before going in to the F300-25? if so, fix that! water will follow the cable to the radio and once it has some momentum, it can follow the cable right inside the radio, also a small crack in the cable will allow capillary action to draw water to the connector and that with the power available will eat a connector off quickly. If the cable comes up and then in from underneath without going above the radio at all then check to make sure the cover is on correctly and the cable stays vertical as much as possible.

WARRANTY VOIDING ADVICE, use at your own risk:
about changing the 8p8c socket, yes if you have the correct tools it can be done. This is not a job for a hobbyist soldering iron though and you will need ROHS compliant solder. Digikey and Mouser both carry the correct socket. If I find the part number again I can PM it to you.

Thanks Douglas,

No cable runs from below with a loop before the radio. We pulled it down Saturday and definite water damage to the ethernet jack. Tried some Deoxit, which cleaned up the jack and it will power up, but can’t maintain a stable ethernet connection. This particular radio has been up about a year, so still under warranty. I will try my hand one the one that failed last fall for fun. Bit rusty on my solder skills but have a good kit. That part number would be handy.

Honestly not sure if it was just a case of the cover not being on tight when installed by our tower tech. He said it was difficult to get off and that it was on tight, but no way to prove that. Since there are not wide spread complaints assuming that’s in the realm of possibility.

The pads are on the small side and lift easily.

I have had 4 F300-25 RMA and two more have failed and it appears to be a fault with the ethernet socket. The symptom is intermittent ethernet connection and like a cable with one leg open. The tell tale is that the radio will no loner have negotiated to 1GHz but will be on 100 Mbps or 10 Mbps or down. Applying inward pressure on the cable before tightening the cable tie seems to resolve for a while. It also appears when temperatures drop so thermal cycling is suggested. One location is on it’s third F300-25. If these radio were not so good I would have dropped them. To the customer the problem is persistant buffering which looks like a poor congested network. This is long before we notice any issues so it is very bad for goodwill and .future sales. I am uncertain that it is the socket and could be incompletely soldered connection to the ethernet transformer or from the comment here of corrosion may the pc board etch not being completely washed from the board during manufacture allowing corrosion to continue when deployed in the field in moist environments. The reason for not the socket is a test from the managed switch connected to one radio detected all pairs OK.
Russ@countrynet NZ

Similar experience as what you describe with similar symptoms. This is the 3rd F300-25 to have the “issue” in a year. This last one hung in the longest at just under a year. Played with in on our bench yesterday and I could get it to fail by simply moving the ethernet cable. Cleaning the jack help that somewhat, at least as far as mainting POE, but the ethernet connection was still intermittent.

My paranoia is starting to kick in as we have a critical F300 link where we need 200+ meg that in turn feeds 3 other back hauls I think we’re going to put up F300 CSM and utilize the F300-25’s as a backup. Perhaps the F400-25 but hearing they are tough to get at the moment.

If you can see any corrosion in the connector then you can guarantee that there is some on the board. So far regular vinegar cleans it off and a little isopropyl for good measure. The ethernet transformer is a fair distance away on the f300-25, so it is unlikely to be damaged by this (they dont like lighting strikes, but not much does!)

It is hard to believe a managed switch when it says the pairs are ok, I have personally been holding the chopped cable and it still insists that its ok. Maybe I have just been too jaded by crap hardware.

We have lots of f300-25’s on our network and we just havent had the issue of a bad connector too much, f200 yes but not the f300-25.

We are moving the ptp links to the f300-csm and e3kL for a few reasons, the biggest is the sealed gland on the bottom the next is the connectorized antenna ports. The f200/f300 dish is nice but the kpp 2ft dish is better and has higher side lobe rejection.

Hi Riverrat,
Maybe the topic got a little bit old but we have the almost the same issue still happening.
We have six units with the exact same problem: it’s getting water in the ethernet jack and it stop working. The device is still reachable by wireless but the ethertnet presents only 10Mbit connection without any communication or presents no link.

That happend with 2 links:

  • only in costumers side (briefly pointed up antenna);
  • never in our side (higher building, pointed down antenna);
  • once a year last three years;
  • always in summer period in Brazil, with more rain in our region;

Our guess it’s the water is infiltrating into the unit sides and accumulating in the back. After a year running and this issue happens we can see a slighly gap in the side joint and dark of dirt.
There is no way the water is coming throught the cable.

One of those was almost full of water when we replace it.

Can you share MSNs of these 2 Force300-25 units? Just sent you the email to further troubleshoot.

We’ve had two more links experiencing this issue since the original posting. We’ve had ongoing issues with these on towers as back hauls. About a year is all we get out of them and then the ethernet port begins “degrading” with intermittent ethernet drops which continue to gradually worsen. We’ve tried all the usual, different switch ports, different switches (currently on Netonix) POE via the switch and the Cambium power supply, grounding, etc and none of it made any difference.

We’ve replaced the cabling several time and currently have them on high quality solid core shielded Cat 6 and connectors, cleaned the jacks, and even tried dialectic grease, again, none of it made any difference. The ports on the F300-25 have always been particularly picky. We’ve had no problems with the F300-16.

We’re actually climbing this weekend to replace both back haul links with AirFiber units. We would like to use F400’s but they are currently being told “maybe 4th quarter” for availability.

Can you please open a support ticket (if already not opened) and it should be checked/troubleshooted what’s exactly happening. Thank you.

@Riverrat please post your final resolution in this, I was following the thread and we to are seeing similar issues arising.

Hi @Riverrat !

Did you have a chance to open the support ticket?

Sorry not yet. Units were pulled down last weekend and set them up to soak and monitor. I’m out and about until Thursday so I’ll get a ticket opened then.


Some of our 300-25s have identically located gaps nearly 3/32" wide!

1 Like

The “problem” unit did not show any indications of water infiltration and we had used dielectric grease when it was installed, yet was still reporting ethernet drops all day every day. We replaced it with an AirFiber link utilizing the same cabling and have not had an issue since. We still have one back haul utilizing F300’s that will be installing AirFiber and leaving the F325s on the tower as a “standby” back up.

As a result of water getting into the ethernet port on the back of the F300-25, we have experienced a second backhaul failure. As you can see from the picture, the first one had moisture in the jack, and the second one had the classic greening and burnt pins. I was curious if anyone else had encountered this issue before. There have been a number of instances this year of heavy storms with high wind-driven rain as well as heavy ice events during the year, plus they have been deployed in several places.

Despite the fact that we are preparing to replace it with a CSM, we still have a few F300-25 backhauls which I am considering sealing with a thin silicon layer to try and prevent this problem from occurring in the future. There is another F300-25t in our fleet that may also be experiencing the problem as we have been experiencing several unexplained network dropouts in the last two weeks, and we will be climbing this weekend in order to investigate. This is how the most recent failure came about.

We have been using the F300-CSM radios on our latest backhauls, and we will be replacing the current F300-25 radio with a CSM radio in the near future.

I may try to replace the ethernet port on the radio myself, just to see if I can do it successfully.


Dont use silicone, use automotive dielectric grease on the cable side connector. Also make sure your cable comes up at least 1ft (30cm) vertically into the radio to prevent water from chasing up the cable jacket into the radio.

The ports are a common part from digikey/mouser/newark and are actually fairly easy to replace as long as you use lots of flux and have the correct tools. A good rework station is a must and solder braid and/or a desoldering gun, do not try with a cheap pencil iron or you will cause damage.